Process control for long chain branching control in polyethylene production

ABSTRACT

Polymerization process control methods for making polyethylene are provided. The process control methods include performing a polymerization reaction in a polymerization reactor to produce the polyethylene, where ethylene, and optionally one or more comonomers, in the polymerization reaction is catalyzed by an electron donor-free Ziegler-Natta catalyst and an alkyl aluminum co-catalyst. A melt flow ratio (I 21 /I 2 ) of the polyethylene removed from the polymerization reactor is measured and an amount of long chain branching (LCB) of the polyethylene from the polymerization reactor is controlled by adjusting a weight concentration of the alkyl aluminum co-catalyst present in the polymerization reactor. In addition, an electron donor-free Ziegler-Natta catalyst productivity of the polyethylene being produced in the polymerization reactor is measured from which the amount of LCB of the polyethylene from the polymerization reactor is determined using the measured electron donor-free Ziegler-Natta catalyst productivity and a predetermined relationship between the electron donor-free Ziegler-Natta catalyst productivity and the LCB.

This application is a Continuation-In-Part of application Ser. No.14/911,665, filed Feb. 11, 2016 and published as U.S. Pub. No.2016/0194421 on Jul. 7, 2016, which claims priority to InternationalApplication PCT/US2014/053652, filed Sep. 2, 2014 and published as WO2015/034804 on Mar. 12, 2015, which claims the benefit of U.S.Provisional Application Ser. No. 61/873,988 filed Sep. 5, 2013, theentire contents of which are incorporated herein by reference in theirentirety.

BACKGROUND

Ziegler-Natta catalysts are widely used to produce polyethylene andcopolymers thereof. There are many varieties and methods for makingZiegler-Natta catalysts, such as depositing a titanium complex on asolid support such as magnesium chloride and/or silica. Ziegler-Nattacatalysts are fairly inexpensive to produce and usually generate polymerproducts at high levels of productivity.

Typical Ziegler-Natta products have a molecular weight distribution(MWD) greater than about 2.0, more commonly greater than about 3.0, anda melt flow ratio (MFR) defined as I₂₁/I₂ ranging from about 24 to about28. Polyethylene films produced from Ziegler-Natta catalyzed resins areknown for excellent toughness and tear properties. Processing propertiesof polyethylene produced using Ziegler-Natta catalysts are also affectedby long-chain branching. For example, long-chain branches, even at verylow concentrations, have a strong effect on the polymer melt behaviorand, thereby, the processing properties.

There is a need, therefore, for the ability to control the amount oflong-chain branching that occurs during the production of polyethyleneresins using Ziegler-Natta catalysts.

SUMMARY

Disclosed herein are polymerization process control methods for makingpolyethylene in which an amount of long-chain branching (LCB) in thepolyethylene is controlled by adjusting an amount of an alkyl aluminumco-catalyst used with an electron donor-free Ziegler-Natta catalystduring the production of the polyethylene. As discussed herein, theprocess control methods of the present disclosure include performing apolymerization reaction in a polymerization reactor to produce thepolyethylene, where ethylene, and optionally one or more comonomers, inthe polymerization reaction is catalyzed by an electron donor-freeZiegler-Natta catalyst and an alkyl aluminum co-catalyst. Theconcentration of the alkyl aluminum co-catalyst is adjusted to bothmanipulate and control the electron donor-free Ziegler-Natta catalystproductivity and a melt flow ratio (MFR) (I₂₁/I₂) of the polyethylene.Surprisingly, it has been discovered that the amount of LCB in thepolyethylene is also controlled by the concentration of the alkylaluminum co-catalyst used in the polymerization process. As discussedherein, the alkyl aluminum co-catalyst can be triethylaluminum (TEAl).

The present disclosure also provides that the polymer MFR and/or theelectron donor-free Ziegler-Natta catalyst productivity may be used forprocess control as an indication of the instant LCB (in the absence ofLCB measurement during the polymerization reaction), where the weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor and/or the alkyl aluminum co-catalyst toZiegler-Natta active metal molar ratio can be adjusted to control theamount of LCB in the polyethylene polymer. It has also been discoveredas the concentration of the alkyl aluminum co-catalyst is reduced for agiven polymerization process, both the electron donor-free Ziegler-Nattacatalyst productivity and the MFR of the polyethylene increase.

The present disclosure also provides for a polymerization processcontrol method that includes performing a polymerization reaction in apolymerization reactor to produce a polyethylene, where thepolymerization reaction is catalyzed by the electron donor-freeZiegler-Natta catalyst and the alkyl aluminum co-catalyst with ethyleneand optionally one or more comonomers to produce the polyethylene. Aportion of the polyethylene is removed from the polymerization reactorand the MFR (I₂₁/I₂) of the polyethylene removed from the polymerizationreactor is measured and the amount of LCB of the polyethylene from thepolymerization reactor is determined using the measured MFR and apredetermined relationship between the melt flow ratio (I₂₁/I₂) and theLCB. A weight concentration of the alkyl aluminum co-catalyst present inthe polymerization reactor can be adjusted to control the LCB of thepolyethylene produced in the polymerization reactor. For example,controlling the amount of LCB includes decreasing the weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor to increase the LCB of the polyethylene producedin the polymerization reactor.

The present disclosure additionally provides for a polymerizationprocess control method that includes performing a polymerizationreaction in a polymerization reactor to produce polyethylene, where thepolymerization reaction is catalyzed by the electron donor-freeZiegler-Natta catalyst and the alkyl aluminum co-catalyst with ethyleneand optionally one or more comonomers to produce the polyethylene. Aportion of the polyethylene is removed from the polymerization reactor.The catalyst productivity of the electron donor-free Ziegler-Nattacatalyst making the polyethylene in the polymerization reactor ismeasured and an amount of LCB of the polyethylene removed from thepolymerization reactor is determined using the measured electrondonor-free Ziegler-Natta catalyst productivity and a predeterminedrelationship between the electron donor-free Ziegler-Natta catalystproductivity and the LCB.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a graphical representation of the Crystallization ElutionFractionation (CEF) data used to calculate the comonomer heterogeneityindex (CHI) for Example 19.

FIGS. 2 and 3 depict graphical representations that compare the CEF dataof Example 18 to comparative example C12 and the CEF data of Example 19to comparative example C13, respectively.

FIG. 4 depicts the graphical representations of the ExtensionalViscosity Fixture (EVF) data at a strain hardening rate of 0.1 s⁻¹ at150° C. for Examples 18 and 19 and comparative examples C12, C13, andC3.

FIG. 5 depicts a graphical representation of the melt strength forExample 1 and comparative examples C3 and C15.

FIG. 6 depicts a graphical representation of the polymer Long ChainBranching (LCB) vs. the concentration of co-catalyst in the resin forExample 20 through Example 23.

FIG. 7 depicts a graphical representation of the polymer MFR (Melt FlowRatio) I₂₁/I₂ vs. the concentration of co-catalyst in the resin forExample 20 through Example 23.

FIG. 8 depicts a graphical representation of the electron donor-freeZiegler-Natta catalyst productivity vs. the concentration of co-catalystin the resin for Example 20 through Example 23.

FIG. 9 depicts a graphical representation of the polymer Long ChainBranching (LCB) vs. the polymer MFR (I₂₁/I₂) for Example 20 throughExample 23.

FIG. 10 depicts a graphical representation of the polymer Long ChainBranching (LCB) vs. the concentration of co-catalyst in the resin forExample 30 and Example 31.

FIG. 11 depicts a graphical representation of the polymer MFR (Melt FlowRatio) I₂₁/I₂ vs. the concentration of co-catalyst in the resin forExample 30 and Example 31.

FIG. 12 depicts a graphical representation of the electron donor-freeZiegler-Natta catalyst productivity vs. the concentration of co-catalystin the resin for Example 30 and Example 31.

FIG. 13 depicts a graphical representation of the polymer Long ChainBranching (LCB) vs. the polymer MFR (I₂₁/I₂) for Example 30 and Example31.

FIG. 14 depicts a graphical representation of the polymer Long ChainBranching (LCB) vs. the electron donor-free Ziegler-Natta catalystproductivity for Example 20 through Example 23.

FIG. 15 depicts a graphical representation of the polymer Long ChainBranching (LCB) vs. the electron donor-free Ziegler-Natta catalystproductivity for Example 30 and Example 31.

DETAILED DESCRIPTION

Disclosed herein are polymerization process control methods for makingpolyethylene in which an amount of long-chain branching (LCB) in thepolyethylene is controlled by adjusting an amount of an alkyl aluminumco-catalyst used with an electron donor-free Ziegler-Natta catalystduring the production of the polyethylene. As discussed herein, theprocess control methods of the present disclosure include performing apolymerization reaction in a polymerization reactor to produce thepolyethylene, where ethylene, and optionally one or more comonomers, inthe polymerization reaction is catalyzed by an electron donor-freeZiegler-Natta catalyst and an alkyl aluminum co-catalyst. Theconcentration of the alkyl aluminum co-catalyst is adjusted to bothmanipulate and control the electron donor-free Ziegler-Natta catalystproductivity and a melt flow ratio (MFR) (I₂₁/I₂) of the polyethylene.Surprisingly, it has been discovered that the amount of LCB in thepolyethylene is controlled by the concentration of alkyl aluminumco-catalyst used in the polymerization process.

The present disclosure also provides that the polymer MFR and/or theelectron donor-free Ziegler-Natta catalyst productivity may be used forprocess control as an indication of the instant LCB (in the absence ofLCB measurement during the polymerization reaction), where the weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor and/or the alkyl aluminum co-catalyst toZiegler-Natta active metal molar ratio can be adjusted to control theamount of LCB in the polyethylene polymer. It has also been discoveredas the concentration of the alkyl aluminum co-catalyst is reduced for agiven polymerization process, both the electron donor-free Ziegler-Nattacatalyst productivity and the MFR of the polyethylene increase.

The present disclosure also provides for a polymerization processcontrol method that includes performing the polymerization reaction inthe polymerization reactor to produce polyethylene, where thepolymerization reaction is catalyzed by the electron donor-freeZiegler-Natta catalyst and the alkyl aluminum co-catalyst with ethylene,and optionally one or more comonomers, to produce the polyethylene. Aportion of the polyethylene is removed from the polymerization reactor.The MFR (I₂₁/I₂) of the polyethylene removed from the polymerizationreactor is measured and the amount of LCB of the polyethylene from thepolymerization reactor is determined using the measured MFR and apredetermined relationship between the MFR (I₂₁/I₂) and the LCB. Aweight concentration of the alkyl aluminum co-catalyst present in thepolymerization reactor is adjusted to control the LCB of thepolyethylene produced in the polymerization reactor. For example,controlling the amount of LCB includes decreasing the weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor to increase the LCB of the polyethylene producedin the polymerization reactor.

The present disclosure also provides methods for making the electrondonor-free Ziegler-Natta catalyst. The method may comprise combining oneor more supports with one or more magnesium-containing compounds underreaction conditions to form a first reacted product. The first reactedproduct may then be combined with one or more chlorinating compoundsselected from one or more aluminum alkyl chlorides, one or more chlorosubstituted silanes, and combinations thereof to form a second reactedproduct. The second reacted product may then be combined with one ormore titanium-containing compounds selected from one or more titaniumalkoxides, one or more titanium halides, and combinations thereof underreaction conditions to form the electron donor-free Ziegler-Nattacatalyst.

In some embodiments, the method of forming the electron donor-freeZiegler-Natta catalyst may comprise combining one or more supports withone or more magnesium-containing compounds under reaction conditions toform a first reacted product; combining one or more aluminum alkylchlorides with the first reacted product under reaction conditions toform a second reacted product; and combining one or more titaniumalkoxides with the second reacted product under reaction conditions toform the electron donor-free Ziegler-Natta catalyst.

In some embodiments, the method of forming the electron donor-freeZiegler-Natta catalyst may comprise combining one or more supports withone or more magnesium-containing compounds under reaction conditions toform a first reacted product; combining one or more chloro substitutedsilanes with the first reacted product under reaction conditions to forma second reacted product; and combining one or more titanium halideswith the second reacted product under reaction conditions to form theelectron donor-free Ziegler-Natta catalyst.

In the above described methods of forming the electron donor-freeZiegler-Natta catalyst, the one or more supports and the one or moremagnesium-containing compounds may be combined with one another in thepresence of one or more diluents. For example, the magnesium-containingcompound and the support may be combined with one another in thepresence of one or more alkanes, one or more aromatic hydrocarbons, oneor more cycloalkanes, or any combination thereof.

In the above described methods of forming the electron donor-freeZiegler-Natta catalyst, the first reacted product and the one or morechlorinating compounds may be combined with one another in the presenceof one or more diluents.

Additionally, the second reacted product and the one or moretitanium-containing compounds may be combined with one another in thepresence of one or more diluents. For example the second reacted productand the one or more titanium-containing compounds may be combined withone another in the presence of one or more diluents to provide theelectron donor-free Ziegler-Natta catalyst mixed with the one or morediluents. In such an embodiment, the method for making the electrondonor-free Ziegler-Natta catalyst may then further comprise removing theone or more diluents from the electron donor-free Ziegler-Natta catalystto provide the electron donor-free Ziegler-Natta catalyst in a powderform.

The electron donor-free Ziegler-Natta catalyst formed by the methodsdescribed herein may be essentially free of donor compounds. Forexample, the electron donor-free Ziegler-Natta catalyst may beessentially free of donor compounds selected from the group consistingof alcohols, thiols, amines, phosphines, ethers, ketones, and esters.

In some embodiments, the one or more supports and the one or moremagnesium-containing compounds may be combined with one another at atemperature of about 20° C. to about 120° C. and mixed for a timeranging from about 30 minutes to about 24 hours to form the firstreacted product. The one or more chlorinating compounds and the firstreacted product may then be combined with one another at a temperatureof about 20° C. to about 120° C. and mixed for a time ranging from about30 minutes to about 24 hours to form the second reacted product. The oneor more titanium-containing compounds and the second reacted product maythen be combined with one another at a temperature of about 20° C. toabout 120° C. and mixed for a time ranging from about 30 minutes toabout 24 hours to form the electron donor-free Ziegler-Natta catalyst.

The above described electron donor-free Ziegler-Natta catalysts may becombined with ethylene in a polymerization reactor at conditionssufficient to produce polyethylene having improved properties. Thepolyethylene may be a homopolymer, or may be a copolymer derived fromethylene and one or more C₃ to C₂₀ alpha-olefin comonomers, or may be acopolymer derived from ethylene and one or more C₃ to C₆ alpha-olefincomonomer

The polyethylene may have a molecular weight distribution (MWD) of about4.5 to about 14, as measured with light scattering detector; a slope ofstrain hardening greater than about 0.75, as measured by extensionalviscosity fixture (EVF); and a melt flow ratio (I₂₁/I₂) greater than orequal to 8.33+(4.17×MWD). The polyethylene may also have a long chainbranching (LCB) greater than about 0.01 per 1,000 carbon atoms and lessthan about 0.07 per 1,000 carbon atoms. In preferred embodiments, thelong chain branches are composed of more than 6 carbon atoms. Thepolyethylene may also have a comonomer homogeneity index (CHI) of lessthan about 0.5.

As discussed herein, the amount of LCB in the polyethylene may becontrolled during the polymerization process by adjusting an amount ofthe alkyl aluminum co-catalyst used with the electron donor-freeZiegler-Natta catalyst during the production of the polyethylene.Adjusting the amount of the alkyl aluminum co-catalyst includesincreasing the amount used and/or decreasing the amount of the alkylaluminum co-catalyst used with the electron donor-free Ziegler-Nattacatalyst during the production of the polyethylene to make the desiredchange in LCB of the polyethylene. The concentration of the alkylaluminum co-catalyst is adjusted to both manipulate and control theelectron donor-free Ziegler-Natta catalyst productivity and a melt flowratio (MFR) (I₂₁/I₂) of the polyethylene. Surprisingly, as theconcentration of the alkyl aluminum co-catalyst is reduced for a givenpolymerization process, both the electron donor-free Ziegler-Nattacatalyst productivity and the MFR of the polyethylene increase. Inaddition, the amount of LCB in the polyethylene is controlled by theconcentration of alkyl aluminum co-catalyst used in the polymerizationprocess. The polyethylene may have a density greater than or equal to0.945 g/cm³ and a melt strength greater than or equal toa×(3.7463×exp(−1.485×log(MI))), wherein a is equal to 1.5, or 1.75, or1.9 and where the logarithm is base 10.

The polyethylene may have a density less than or equal to 0.945 g/cm³and a melt strength greater than or equal toa×(3.7463×exp(−1.485×log(MI))), wherein a is equal to 1.2, or 1.5, or1.9 and where the logarithm is base 10.

Support

As used herein, the terms “support” and “carrier” are usedinterchangeably and refer to any support material or combination ofsupport materials. The support can be or include one or more porousmaterials, such as talc, inorganic oxides, and inorganic chlorides.Other supports can be or include resinous materials such as polystyrene,functionalized or crosslinked organic polymers such as polystyrenedivinyl benzene polyolefins or other polymeric compounds, or any otherorganic or inorganic support material, or mixtures thereof. The supportcan be an amorphous material, crystalline material, or a mixture ofamorphous and crystalline material. Illustrative inorganic oxides caninclude one or more metal oxides of Group 2, 3, 4, 5, 12, 13, or 14elements. For example, the inorganic oxide can include, but is notlimited to, alumina, silica, titania, zirconia, boria, zinc oxide,magnesia, or any combination thereof. Illustrative combinations ofinorganic oxides can include, but are not limited to, alumina-silica,silica-titania, alumina-silica-titania, alumina-zirconia,alumina-titania, and the like. In at least one example, the support canbe or include alumina, silica, or a combination thereof. As used herein,all reference to the Periodic Table of the Elements and groups thereofis to the New Notation published in “Hawley's Condensed ChemicalDictionary,” Thirteenth Edition, John Wiley & Sons, Inc., (1997)(reproduced there with permission from IUPAC), unless reference is madeto the Previous IUPAC form noted with Roman numerals (also appearing inthe same), or unless otherwise noted.

The support can include one or more hydroxyl groups, e.g., a supportcontaining silica can include silanol (Si—OH) groups, in and/or on thesupport. The hydroxyl groups can be present in an amount ranging from alow of about 0.1 millimoles (mmol), about 0.2 mmol, about 0.3 mmol,about 0.4 mmol, or about 0.5 mmol to a high of about 1 mmol, about 2mmol, about 3 mmol, about 4 mmol, or about 5 mmol per gram of thesupport. For example, the hydroxyl groups can be present in an amount ofabout 0.3 mmol to about 5 mmol, about 0.5 mmol to about 2 mmol, about0.5 mmol to about 0.9 mmol, or about 0.6 mmol to about 1 mmol per gramof the support. If the number of hydroxyl groups present on the supportis greater than a desired amount, the excess hydroxyl groups can beremoved by heating the carrier for a sufficient time at a sufficienttemperature. For example, a relatively small number of hydroxyl groupscan be removed by heating the support to a temperature of about 150° C.to about 250° C., whereas a relatively large number of hydroxyl groupsmay be removed by heating at a temperature of about 500° C. to about800° C., or about 550° C. to 650° C. The support can be heated for atime ranging from about 1 hour to about 20 hours, or about 4 hours toabout 16 hours, for example. The surface hydroxyl concentration insilica can be determined according to J. B. Peri, and A. L. Hensley,Jr., J. Phys. Chem., vol. 72, No. 8, p. 2926 (1968). An alternative toheating the support to remove at least a portion of any hydroxyl groupscan include chemical means. For example, a desired fraction of hydroxylgroups can be reacted with a chemical agent such as a hydroxyl-reactiveorganoaluminum compound, e.g., triethylaluminum.

Supports that include two or more inorganic oxides can have any ratio oramount of each inorganic oxide, relative to one another. For example, analumina-silica catalyst support can include from about 1 wt % alumina toabout 99 wt % alumina, based on the total amount of alumina and silica.In another example, an alumina-silica catalyst support can have analumina concentration ranging from a low of about 2 wt %, about 5 wt %,about 15 wt %, or about 25 wt % to a high of about 50 wt %, about 60 wt%, about 70 wt %, or about 90 wt %, based on the total amount of aluminaand silica. A mixed inorganic oxide support can be prepared using anysuitable method. For example, a silica support can be mixed, blended,contacted, or otherwise combined with one or more aluminum compounds toproduce a silica support and aluminum compound(s) mixture. In anotherexample, the silica support can be mixed with the one or more aluminumcompounds in a water and/or alcohol solution and dried to produce thesilica support and aluminum compound(s) mixture. Suitable alcohols caninclude, but are not limited to, alcohols having from 1 to 5 carbonatoms, and mixtures or combinations thereof. For example, the alcoholcan be or include methanol, ethanol, propan-1-ol, propan-2-ol, and thelike. Suitable aluminum compounds can include, but are not limited to,aluminum monoacetate ((HO)₂AlC₂H₃O₂), aluminum diacetate(HOAl(C₂H₃O₂)₂), and aluminum triacetate (Al(C₂H₃O₂)₃), aluminumhydroxide (Al(OH)₃), aluminum diacetate hydroxide (Al(OAc)₂OH), aluminumtri-acetylacetonate, aluminum fluoride (AlF₃), sodiumhexafluoroaluminate (Na₃AlF₆), or any combination thereof.

The silica support and aluminum compound(s) mixture can be heated(calcined) in the presence of one or more inert gases, oxidants,reducing gases, or in any order/combination thereof to produce analumina-silica catalyst support. As used herein, the term “oxidant” caninclude, but is not limited to, air, oxygen, ultra-zero air,oxygen/inert gas mixtures, or any combination thereof. Inert gases caninclude, but are not limited to, nitrogen, helium, argon, orcombinations thereof. Reducing gases can include, but are not limitedto, hydrogen, carbon monoxide, or combinations thereof.

The silica support and aluminum compound(s) mixture can be heated to afirst temperature under nitrogen gas or other inert gas. After heatingto the first temperature the nitrogen gas can be stopped, one or moreoxidants can be introduced, and the temperature can be increased to asecond temperature. For example, the silica support and aluminumcompound(s) mixture can be heated under an inert atmosphere to atemperature of about 200° C., the oxidant can be introduced, and themixture can then be heated to a temperature of from about 450° C. toabout 1,500° C. to produce an alumina-silica catalyst support. Thesecond temperature can range from a low of about 250° C., about 300° C.,about 400° C., or about 500° C. to a high of about 600° C., about 650°C., about 700° C., about 800° C., or about 900° C. For example, thesecond temperature can range from about 400° C. to about 850° C., about800° C. to about 900° C., about 600° C. to about 850° C., or about 810°C. to about 890° C. The silica support and aluminum compound(s) mixturecan be heated and held at the second temperature for a period of timeranging from about 1 minute to about 100 hours. For example, the silicasupport and alumina compound(s) mixture can be heated and held at thesecond temperature for a time ranging from a low of about 30 minutes,about 1 hour, or about 3 hours to a high of about 10 hours, about 20hours, or about 50 hours. In one or more embodiments, the silica supportand alumina compound(s) mixture can be heated from ambient temperatureto the second or upper temperature without heating to an intermediate orfirst temperature. The silica support and alumina compound(s) mixturecan be heated under a nitrogen or other inert atmosphere initially,which can be modified to include the one or more oxidants or theatmosphere can be or include the one or more oxidants at the initialheating from ambient temperature.

The support can be mixed, blended, contacted, or otherwise combined withone or more sources of halide ions, sulfate ions, or a combination ofanions to produce an inorganic oxide catalyst support and anion mixture,which can be heated or calcined to produce a suitable support. Thesupport can be contacted with bromine, fluorine, chlorine, compoundscontaining bromine, fluorine, and/or chlorine, or any combinationthereof. Suitable supports can include, but are not limited to,brominated silica, brominated silica-titanic, fluorinated silica,fluorinated silica-alumina, fluorinated silica-zirconia,fluorinated-chlorinated silica, fluorinated silica-titania, chlorinatedsilica, sulfated silica, or any combination thereof. The support canalso be treated with one or more metal ions in addition to or in lieu ofthe one or more halide ion sources and/or sulfate ion sources.Illustrative metal ions can include, but are not limited to, copper,gallium, molybdenum, silver, tin, tungsten, vanadium, zinc, or anycombination thereof. Suitable activated supports can include thosediscussed and described in PCT Publication No. WO 2011/103402.

The support can have an average particle size ranging from a low ofabout 0.1 μm, about 0.3 μm, about 0.5 μm, about 1 μm, about 5 μm, about10 μm, or about 20 μm to a high of about 50 μm, about 100 μm, about 200μm, or about 500 μm. The support can have an average pore size rangingfrom about 10 Å to about 1,000 Å, preferably from about 50 Å to about500 Å, and more preferably from about 75 Å to about 350 Å. The supportcan have a pore volume ranging from a low of about 0.01 cm³/g, about 0.1cm³/g, about 0.8 cm³/g, or about 1 cm³/g to a high of about 2 cm³/g,about 2.5 cm³/g, about 3 cm³/g, or about 4 cm³/g. Internal porosity ofthe support can be determined by a technique termed BET-technique,described by S. Brunauer, P. Emmett and E. Teller in Journal of theAmerican Chemical Society, 60, pp. 209-319 (1938). The support can havea surface area ranging from a low of about 1 m²/g, about 50 m²/g, orabout 100 m²/g to a high of about 400 m²/g, about 500 m²/g, or about 800m²/g. The surface area of the support can be measured in accordance withthe above-mentioned BET-technique, with use of the standardized methodas described in British Standards BS 4359, Volume 1, (1969).

Suitable commercially available silica supports can include, but are notlimited to, ES757, ES70, and ES70W available from PQ Corporation.Additional suitable commercially available silica supports can include,but are not limited to, Sylopol® 948, Sylopol® 952, and Sylopol® 955,available from W.R. Grace & Co. Suitable commercially availablesilica-alumina supports can include, but are not limited to, SIRAL® 1,SIRAL® 5, SIRAL® 10, SIRAL® 20, SIRAL® 28M, SIRAL® 30, and SIRAL® 40,available from SASOL®. Suitable supports can be as described in U.S.Pat. Nos. 4,173,547; 4,701,432; 4,808,561; 4,912,075; 4,925,821;4,937,217; 5,008,228; 5,238,892; 5,240,894; 5,332,706; 5,346,925;5,422,325; 5,466,649; 5,466,766; 5,468,702; 5,529,965; 5,554,704;5,629,253; 5,639,835; 5,625,015; 5,643,847; 5,665,665; 5,698,487;5,714,424; 5,723,400; 5,723,402; 5,731,261; 5,759,940; 5,767,032; and5,770,664; and WO 95/32995; WO 95/14044; WO 96/06187; and WO 97/02297.

Magnesium-Containing Compound

The one or more magnesium-containing compounds can be represented by theformula R¹—Mg—R², where R¹ and R² are independently selected from thegroup consisting of hydrocarbyl groups, and halogen atoms. Suitablehydrocarbyl groups can include, but are not limited to, alkyl groups,aryl groups, and alkoxy groups. The alkyl groups, and/or alkoxy groupscan include from 1 to 12 carbon atoms, or from 1 to 10 carbon atoms, orfrom 1 to 8 carbon atoms, or from 1 to 6 carbon atoms, or from 1 to 4carbon atoms. The aryl groups can include from 6 to 12 carbon atoms, orfrom 6 to 10 carbon atoms, or from 6 to 8 carbon atoms. Suitablehalogens can include fluoride, chloride, and bromide.

Illustrative magnesium-containing compounds can include, but are notlimited to, dialkylmagnesiums, dicycloalkylmagnesiums, diarylmagnesiums,alkylmagnesium halides, or any combination thereof. Illustrativedialkylmagnesiums can include, but are not limited to, diethylmagnesium,dipropylmagnesium, di-isopropylmagnesium, di-n-butylmagnesium,di-isobutylmagnesium, diamylmagnesium, di-n-octylmagnesium,di-n-hexylmagnesium, di-n-decylmagnesium, di-n-dodecylmagnesium, or anycombination thereof. Illustrative dicycloalkylmagnesiums can include,but are not limited to, dicyclohexylmagnesium, dicyclopentylmagnesium,or any combination thereof. Illustrative diarylmagnesiums can include,but are not limited to, dibenzylmagnesium, ditolylmagnesium,dixylylmagnesium, or any combination thereof. Illustrative magnesiumalkyls that include two different alkyl groups can include, but are notlimited to, ethyl-n-propylmagnesium, ethyl-n-butylmagnesium,amyl-n-hexylmagnesium, n-butyl-s-butylmagnesium,n-butyl-n-octylmagnesium, or any combination thereof. Illustrativealkymagnesium halides can include, but are not limited to,methylmagnesium chloride, ethylmagnesium chloride, n-butylmagnesiumchloride, t-butylmagnesium chloride, isopropylmagnesium chloride,methylmagnesium bromide, ethylmagnesium bromide, n-butylmagnesiumbromide, or any combination thereof.

It should be noted that magnesium alkyls may contain a mixture ofmolecules. For example, ethylmagnesium chloride may contain a mixture ofmolecules other than ethylmagnesium chloride, per se. For example, if aliquid or solvent is combined with ethylmagnesium chloride, theethylmagnesium chloride may disproportionate to form a mixture ofmagnesium dichloride and diethylmagnesium. Such mixtures are encompassedwithin the general formula R¹MgR². Accordingly, it should be understoodthat compositions of the formula R¹—Mg—R² and compositionsrepresentative thereof are intended to represent the overall empiricalformula of these compositions rather than to set forth the molecularformula of these compositions.

First Reacted Product

The support and the magnesium-containing compound can be combined withone another to provide or form a first mixture or first reacted product.The support and the magnesium-containing compound can at least partiallyreact with one another during mixing thereof. Said another way, thesupport and the magnesium-containing compound can be combined with oneanother under reaction conditions such that the support and themagnesium containing compound at least partially react with one anotherto form a reacted first mixture or reacted first product. For example,if the support contains one or more hydroxyl groups, themagnesium-containing compound can react with at least some of thehydroxyl groups to produce a reacted first mixture or first reactedproduct.

The mixture of the support and the magnesium-containing compound can beheated to a temperature ranging from a low of about 20° C., about 25°C., or about 30° C. to a high of about 60° C., about 75° C., or about120° C., for example, with suitable ranges comprising the combination ofany lower temperature and any upper temperature. If the diluent ispresent, the temperature of the mixture can be maintained below aboiling point of the diluent. The support and the magnesium-containingcompound can be mixed, blended, stirred, or otherwise agitated for atime ranging from a low of about 15 minutes, about 30 minutes, about 1hour, about 2 hours, or about 3 hours to a high of about 5 hours, about10 hours, about 15 hours, about 20 hours, about 25 hours, or more. Thesupport and the magnesium-containing compound can be combined with oneanother and mixed under a vacuum, e.g., 50 kPa. The support and themagnesium-containing compound can be combined with one another and mixedat atmospheric pressure. The support and the magnesium-containingcompound can be combined with one another and mixed under pressure,e.g., a pressure ranging from about 102 kPa to about 500 kPa. Thesupport and the magnesium-containing compound can be combined with oneanother under an inert atmosphere. Inert atmospheres can be or include,but are not limited to, nitrogen, argon, helium, or any combinationthereof. The amount of the magnesium-containing compound combined withthe support can range from a low of about 0.2 mmol, about 0.5 mmol,about 1 mmol, about 1.5 mmol, or about 2 mmol to a high of about 3 mmol,about 4 mmol, about 6 mmol, about 8 mmol, or about 12 mmol per gram ofthe support, with suitable ranges comprising the combination of anylower amount and any upper amount. For example, the amount of themagnesium-containing compound combined with the support can range fromabout 0.3 mmol to about 10 mmol, about 1 mmol to about 7 mmol, about 1.5mmol to about 5 mmol, about 1.5 mmol to about 4 mmol, or about 2 mmol toabout 3 mmol of the magnesium-containing compound per gram of thesupport.

If the support is added to the magnesium-containing compound or themagnesium-containing compound is added to the support, the support orthe magnesium-containing compound can be added all at once or over aperiod of time. The magnesium-containing compound can be added over aperiod of time ranging from a low of about 1 minute, about 5 minutes,about 10 minutes or about 15 minutes to a high of about 45 minutes,about 1 hour, about 2 hours, about 4 hours, about 6 hours or more. Forexample, the magnesium-containing compound can be added to the supportover a time period of about 15 minutes to about 45 minutes, about 20minutes to about 1 hour, or about 30 minutes to about 1.5 hours. Thesupport and the magnesium-containing compound can be continuously orintermittently stirred during the time the magnesium-containing compoundis added to the support.

The support and the magnesium-containing compound can be combined withone another in the presence of one or more diluents to form a solutionor slurry thereof. The diluent, if present, can be any liquid medium orcombination of liquid mediums suitable for forming a slurry of thesupport, the magnesium-containing compound, or the mixture of thesupport and magnesium-containing compound. Illustrative diluents caninclude, but are not limited to, one or more alkanes, one or morearomatic hydrocarbons, one or more cycloalkanes, or any combinationthereof. Illustrative alkanes can include, but are not limited to,pentane, hexane, heptane, octane, nonane, decane, structural isomersthereof, stereoisomers thereof, enantomers thereof, or any combinationthereof. Illustrative aromatic hydrocarbons can include, but are notlimited to, benzene, toluene, xylenes, o-xylene, m-xylene, p-xylene, orany combination thereof. Illustrative cycloalkanes can include, but arenot limited to, cyclohexane, methylcyclohexane, or a combinationthereof.

The amount of the diluent, if present, can be sufficient to produce aslurry of the support and the magnesium-containing compound. The amountof diluent can range from a low of about 0.5 g, about 1 g, about 2 g, orabout 2.5 g to a high of about 5 g, about 7 g, about 10 g, or about 25 gper gram of the support, with suitable ranges comprising the combinationof any lower amount and any upper amount. For example, the amount ofdiluent, if present, can range from about 1.5 g to about 25 g, about 2 gto about 20 g, about 1 g to about 15 g, about 2.5 g to about 6 g, about0.5 g to about 8 g, or about 2.5 g to about 5.5 g per gram of thesupport.

The support and the magnesium-containing compound can be combined withone another in any suitable container or vessel. The container can be acontainer capable of being closed or sealed. The container can includeone or more devices, systems, or combination thereof capable of mixing,blending, or otherwise agitating the mixture of the support and themagnesium-containing compound. For example, the container can includeone or more mixing devices such as one or more mechanical/power mixersand/or acoustic mixers such as sonic mixers. The container can includeone or more heating jackets, heating coils, internal heating elements,cooling jackets, cooling coils, internal cooling elements, or the like,capable of controlling or adjusting a temperature therein.

Second Reacted Product

After the support and magnesium-containing compound have been mixedand/or at least partially reacted with one another for a desired amountof time, one or more chlorinating compounds can be combined with thefirst mixture or the first reacted product to produce or form a secondmixture or second reacted product. Illustrative chlorinating compoundscan be or include, but are not limited to, aluminum alkyl chlorides,halo substituted silanes containing one or more chlorine atoms, fluorineatoms, bromine atoms, or any combination thereof, organic chlorides, orany combination thereof. Illustrative aluminum alkyl chlorides caninclude, but are not limited to, diethylaluminum chloride,diisobutylaluminum chloride, ethylaluminum dichloride, ethylaluminumsesquichloride, isobutylaluminum dichloride, diethylaluminum bromide, orany combination thereof. Illustrative halo substituted silanes caninclude, but are not limited to, dimethyldichlorosilane,chlorotrimethylsilane, methyltrichlorosilane, diethyldichlorosilane,t-butyldimethylsilyl chloride, n-butyltrichlorosilane,triethoxysilylchloride, trimethoxysilylchloride, tetrachlorosilane,tetrabromosilane, dimethyldibromosilane, trimethylbromosilane, or anycombination thereof. Illustrative organic chlorides can include, but arenot limited to t-butyl chloride, tetrachloromethane, chloroform, methylchloride, tribromomethane, tetrabromomethane, or any combinationthereof. In one or more embodiments, the one or more chlorinatingcompounds can be limited to either one or more aluminum alkyl chloridesor one or more halo substituted silanes. In one or more embodiments, theone or more chlorinating compounds can include at least one aluminumalkyl chloride and at least one halo substituted silane.

The chlorinating compound and the first reacted product can at leastpartially react with one another to produce a second reacted product.Said another way, the mixture of the first reacted product and thechlorinating compound can be combined with one another under reactionconditions such that the first reacted product and the chlorinatingcompound at least partially react with one another to form a reactedsecond mixture or reacted second product. For example, the chlorinatingcompound can react with the magnesium containing compound in the firstreacted product to produce the reacted second mixture or second reactedproduct.

The chlorinating compound can be added to the first reacted product orconversely the first reacted product can be added to the chlorinatingcompound. The chlorinating compound can be combined directly with thefirst reacted product or the chlorinating compound can be in the form ofa solution or slurry. For example, the chlorinating compound can becombined with one or more diluents to form a solution or slurry thereof.The solution or slurry of the chlorinating compound can be combined withthe first reacted product to produce the second mixture or secondreacted product. Suitable diluents can include, but are not limited to,the one or more alkanes, the one or more aromatic hydrocarbons, the oneor more cycloalkanes, or any combination thereof, discussed anddescribed above.

The chlorinating compound and the first reacted product can be combinedwith one another in any suitable container or vessel. For example, thechlorinating compound can be combined with the first reacted productwithin the same vessel the first reacted product was produced in. Thechlorinating compound and the first reacted product can besimultaneously combined with one another in the container or vessel. Ifthe chlorinating compound is added to the first reacted product or thefirst reacted product is added to the chlorinating compound, thechlorinating compound or the first reacted product can be added all atonce or over a period of time. For example, the chlorinating compoundcan be added to the first reacted product all at one time. In anotherexample, the chlorinating compound can be added to the first reactedproduct over a period of time ranging from a low of about 1 minute,about 5 minutes, about 10 minutes, or about 15 minutes to a high ofabout 45 minutes, about 1 hour, about 2 hours, about 4 hours, about 6hours, or more. In another example, the chlorinating compound can beadded to the first reacted product over a period of time of about 15minutes to about 45 minutes, about 20 minutes to about 1 hour, or about30 minutes to about 1.5 hours. The chlorinating compound and the firstreacted product can be continuously or intermittently stirred during thetime the chlorinating compound is added to the first reacted product.

The amount of the chlorinating compound combined with the first reactedproduct can range from a low of about 0.2 mmol, about 0.5 mmol, about 1mmol, about 1.5 mmol, or about 2 mmol to a high of about 5 mmol, about 7mmol, about 10 mmol, about 15 mmol, or about 20 mmol per gram of thesupport, with suitable ranges comprising the combination of any loweramount and any upper amount. For example, the second reacted product cancontain about 0.25 mmol to about 20 mmol, about 1 mmol to about 10 mmol,about 1.5 mmol to about 7 mmol, or about 2 mmol to about 5 mmol of thechlorinating compound per gram of the support.

The mixture of the first reacted product and the chlorinating compoundcan be heated to a temperature ranging from a low of about 20° C., about25° C., or about 30° C. to a high of about 60° C., about 75° C., orabout 120° C., for example, with suitable ranges comprising thecombination of any lower temperature and any upper temperature. If thediluent is present, the temperature of the second mixture can bemaintained below a boiling point of the diluent. The chlorinatingcompound and the first reacted product can be mixed, blended, stirred,or otherwise agitated for a time ranging from a low of about 15 minutes,about 30 minutes, about 1 hour, about 2 hours, or about 3 hours to ahigh of about 5 hours, about 10 hours, about 15 hours, about 20 hours,about 25 hours, or more. The chlorinating compound and the first reactedproduct can be combined with one another and mixed under a vacuum, e.g.,50 kPa. The chlorinating compound and the first reacted product can becombined with one another and mixed at atmospheric pressure. Thechlorinating compound and the first reacted product can be combined withone another and mixed under pressure, e.g., a pressure ranging fromabout 102 kPa to about 500 kPa. The support and the first reactedproduct and the chlorinating compound can be combined with one anotherunder an inert atmosphere.

Third Reacted Product

After the chlorinating compound and the first reacted product have beenmixed and/or reacted with one another for a desired amount of time, oneor more titanium-containing compounds can be combined with the secondmixture or second reacted product to produce or form the electrondonor-free Ziegler-Natta catalyst. The titanium-containing compound andthe second reacted product can at least partially react with one anotherduring mixing thereof. Said another way, the second reacted product canbe combined with the one or more titanium-containing compounds underreaction conditions to produce or form the electron donor-freeZiegler-Natta catalyst. For example, the titanium-containing compoundcan react with the second reacted product to produce a reacted thirdmixture or catalyst. The electron donor-free Ziegler-Natta catalyst caninclude the reaction product between the titanium-containing compoundand the second reacted product.

Illustrative titanium-containing compounds can include, but are notlimited to, one or more titanium halides, one or more titaniumalkoxides, one or more titanium amides, or any combination thereof.Illustrative titanium halides can include, but are not limited to,titanium (IV) chloride, titanium (IV) bromide, titanium (IV) fluoride,titanium (IV) iodide, or any combination thereof. Illustrative titaniumalkoxides can include, but are not limited to, tetraisopropyltitanate,titanium (IV) ethoxide, titanium (IV) n-butoxide, titanium (IV)t-butoxide, or any combination thereof. Illustrative titanium amides caninclude, but are not limited to, tetrakis(dimethylamine)titanium(IV).

The one or more titanium-containing compounds can be added to the secondreacted product or conversely the second reacted product can be added tothe titanium-containing compounds. The titanium-containing compound canbe combined directly with the second reacted product or thetitanium-containing compound can be in the form of a solution or slurry.For example, the titanium-containing compound can be combined with oneor more diluents to form a solution or slurry thereof. The solution orslurry of the titanium-containing compound can be combined with thesecond reacted product to produce the electron donor-free Ziegler-Nattacatalyst. Suitable diluents can include, but are not limited to, the oneor more alkanes, the one or more aromatic hydrocarbons, the one or morecycloalkanes, or any combination thereof, discussed and described above.

The titanium-containing compound and the second reacted product can becombined with one another in any suitable container or vessel. Forexample, the titanium-containing compound can be combined with thesecond reacted product within the same vessel the second reacted productwas produced in. The titanium-containing compound and the second reactedproduct can be simultaneously combined with one another in the containeror vessel. If the titanium-containing compound is added to the secondreacted product or the second reacted product is added to thetitanium-containing compound, the titanium-containing compound or thesecond reacted product can be added all at once or over a period oftime. For example, the titanium-containing compound can be added to thesecond reacted product all at one time. In another example, thetitanium-containing compound can be added to the second reacted productover a period of time ranging from a low of about 1 minute, about 5minutes, about 10 minutes or about 15 minutes to a high of about 45minutes, about 1 hour, about 2 hours, about 4 hours, about 6 hours ormore. In another example, the titanium-containing compound can be addedto the second reacted product over a time period of about 15 minutes toabout 45 minutes, about 20 minutes to about 1 hour, or about 30 minutesto about 1.5 hours. The titanium-containing compound and the secondreacted product can be continuously or intermittently stirred during thetime the titanium-containing compound is added to the second reactedproduct.

The amount of the titanium-containing compound in the electrondonor-free Ziegler-Natta catalyst can range from a low of about 0.05mmol, about 0.1 mmol, about 0.5 mmol, about 1 mmol, or about 2 mmol to ahigh of about 3 mmol, about 4 mmol, about 6 mmol, about 8 mmol, or about12 mmol per gram of the support, with suitable ranges comprising thecombination of any lower amount and any upper amount. For example, theelectron donor-free Ziegler-Natta catalyst can contain about 0.1 mmol toabout 8 mmol, about 0.5 mmol to about 6 mmol, about 1 mmol to about 4mmol, or about 2 mmol to about 3 mmol of the titanium-containingcompound per gram of the support.

The mixture of the titanium-containing compound and second reactedproduct can be heated to a temperature ranging from a low of about 20°C., about 25° C., or about 30° C. to a high of about 60° C., about 75°C., or about 120° C., for example, with suitable ranges comprising thecombination of any lower temperature and any upper temperature. If thediluent is present, the temperature of the second mixture can bemaintained below a boiling point of the diluent. The titanium-containingcompound and the second reacted product can be mixed, blended, stirred,or otherwise agitated for a time ranging from a low of about 15 minutes,about 30 minutes, about 1 hour, about 2 hours, or about 3 hours to ahigh of about 5 hours, about 10 hours, about 15 hours, about 20 hours,about 25 hours, or more. The titanium-containing compound and the secondreacted product can be combined with one another and mixed under avacuum, e.g., 50 kPa. The titanium-containing compound and the secondreacted product can be combined with one another and mixed atatmospheric pressure. The titanium-containing compound and the secondreacted product can be combined with one another and mixed underpressure, e.g., a pressure ranging from about 102 kPa to about 500 kPa.The second reacted product and the titanium-containing compound can becombined with one another under an inert atmosphere. Inert atmospherescan be or include, but are not limited to, nitrogen, argon, or acombination thereof.

It is also possible within the practice of the invention to control theco-catalyst not only as a mole ratio to the titanium or other activemetal on the electron donor-free Ziegler-Natta catalyst, but also oralternatively on the basis of the co-catalyst concentration in the resinon a weight basis. This may prove advantageous where the electrondonor-free Ziegler-Natta catalyst productivity is changing, causing thedenominator in the ratio to move.

If a diluent is used in preparation of the electron donor-freeZiegler-Natta catalyst, e.g., in the preparation of the first reactedproduct, the second reacted product, and/or the mixture of thetitanium-containing compound and the second reacted product, at least aportion of the diluent can be removed. The diluent can be removed usingany suitable process. For example, the diluent can be removed from theelectron donor-free Ziegler-Natta catalyst by placing the slurriedcatalyst under a vacuum, heating the slurry to a temperature sufficientto vaporize the diluent, or a combination thereof to produce a dried,free-flowing catalyst. As such, the electron donor-free Ziegler-Nattacatalyst can be in the form of a slurry, i.e., the diluent was used inproducing the electron donor-free Ziegler-Natta catalyst, or theelectron donor-free Ziegler-Natta catalyst can be in the form of apowder, i.e., either no diluent was used or, if the diluent was presenta sufficient amount of the diluent was removed therefrom to produce thepowdered catalyst. In one or more embodiments, the electron donor-freeZiegler-Natta catalyst can have a crystalline phase or structure, anamorphous phase or structure, or a mixture of crystalline and amorphousphases.

In one or more embodiments, if the electron donor-free Ziegler-Nattacatalyst includes one or more aluminum alkyl chlorides as thechlorinating compound, the titanium-containing compound can include theone or more titanium alkoxides, the one or more titanium amides, or thecombination thereof. In one or more embodiments, if the electrondonor-free Ziegler-Natta catalyst includes one or more substitutedsilanes as the chlorinating compound, the titanium-containing compoundcan include one or more titanium halides. Said another way, when thetitanium-containing compound is a titanium halide, the chlorinatingcompound can be one or more substituted silanes. Likewise, when thetitanium-containing compound is a titanium alkoxide and/or a titaniumamide, the chlorinating compound can be one or more aluminum alkylchlorides. In at least one specific embodiment, when the chlorinatingcompound includes one or more aluminum alkyl chlorides, the chlorinatingcompound can be free of or essentially free of any intentionally addedsubstituted silanes. In at least one other specific embodiment, when thechlorinating compound includes one or more substituted silanes, thechlorinating compound can be free of or essentially free of anyintentionally added aluminum alkyl chlorides.

In one or more embodiments, the electron donor-free Ziegler-Nattacatalyst is free or essentially free from any electron donors or donorcompounds. As used herein the terms “essentially free from any electrondonors” and “essentially free from any donor compounds” are usedinterchangeably and mean that the electron donor-free Ziegler-Nattacatalyst contains less than about 1 wt % of an electron donor, based onthe total weight of the electron donor-free Ziegler-Natta catalyst. Forexample, catalyst essentially free from any electron donors can containless than about 1 wt %, less than about 0.7 wt %, less than about 0.5 wt%, less than about 0.3 wt %, less than about 0.1 wt %, or less thanabout 0.05 wt % of an electron donor, based on the total weight of theelectron donor-free Ziegler-Natta catalyst. As used herein, the term“electron donor” refers to compounds that donate one or more electronsused in chemical covalent and/or dative bond and/or adduct formation.Electron donors include alcohols, thiols, amines, phosphines, ethers,ketones, and esters.

As used herein, the term “alcohol” refers to a chemical compound havingthe formula ROH, where R is any substituted or unsubstituted hydrocarbylgroup. Illustrative alcohols include aliphatic alcohols, cyclicalcohols, and aromatic alcohols. Aliphatic alcohols can have from 1 toabout 25 carbon atoms, for example. Illustrative aliphatic alcoholsinclude methanol, ethanol, propanol, isopropanol, butanol,2-ethylhexanol, and 1-dodecanol. Illustrative cyclic alcohols includecyclohexanol. Illustrative aromatic alcohols include t-butyl phenol.

As used herein the term “ether” refers to a chemical compound having theformula R—O—R′, where R and R′ are independently selected fromsubstituted and unsubstituted hydrocarbyl groups, or R and R′ form afused ring, where the fused ring is saturated or unsaturated.Illustrative ethers that contain hydrocarbyl groups include diethylether, diisopropyl ether, di-n-butyl ether, ethylisopropyl ether,methylbutyl ether, methylallyl ether, and ethylvinyl ether. Illustrativeethers that contain a fused ring include tetrahydrofuran, and 2-methyltetrahydrofuran.

As used herein, the term “ketone” refers to a chemical compound havingthe formula R(C═O)R′, where R and R′ are independently selected fromsubstituted and unsubstituted hydrocarbyl groups and as otherwisedescribed above with reference to ethers. Illustrative ketones includeacetone, methylethyl ketone, cyclohexanone, cyclopentylmethyl ketone,3-bromo-4-heptanone, and 2-chlorocyclopentanone. Other suitable ketonesmay include other functional groups such as unsaturations, as inallylmethyl ketone.

As used herein, the term “ester” refers to a chemical compound havingthe formula R(C═O)OR′, where the carbon atom of the carbonyl group formsone bond to a carbon atom and another bond to an oxygen atom, and whereR and R′ are independently selected from substituted or unsubstitutedhydrocarbyl groups. Illustrative esters can include alkyl esters ofaliphatic and aromatic carboxylic acids, cyclic esters, saturatedesters, and halogenated esters. Specific examples of esters can includemethyl acetate, ethyl acetate, ethyl propionate, methyl propionate, andethyl benzoate.

One or more alkyl aluminum co-catalysts or activators can be combinedwith the electron donor-free Ziegler-Natta catalyst. Suitableco-catalysts can include, but are not limited to, organometalliccompounds such as aluminum alkyl compounds. Illustrative aluminum alkylcompounds can include, but are not limited to, dialkylaluminum halidese.g., dialkyaluminum chlorides, dialkylaluminum hydrides, alkylaluminumhalides, e.g. alkylaluminum chlorides, and trialkylaluminum compounds.The alkyl group in aluminum alkyl compounds can include from 1 to 18 orfrom 1 to 12, or from 1 to 10, or from 1 to 8, or from 1 to 6 carbonatoms. For example, the alkyl group in aluminum alkyl compounds can bemethyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl, heptyl, or octyl.Preferably, the alkyl aluminum co-catalyst can be or includetrialkylaluminum compounds, in which the alkyl group includes from 1 to18 or from 1 to 12, or from 1 to 10, or from 1 to 8, or from 1 to 6carbon atoms. Illustrative trialkylaluminum compounds can include, butare not limited to, triethylaluminum, triisobutylaluminum,tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum,trimethylaluminum, or any combination thereof. A preferred alkylaluminum co-catalyst is triethylaluminum (TEAl). Other suitable alkylaluminum co-catalysts can include those discussed and described in U.S.Pat. Nos. 3,787,384; 4,148,754; and 4,481,301.

The amount of the alkyl aluminum co-catalyst that can be combined withthe electron donor-free Ziegler-Natta catalyst can range from a low ofabout 0.1 mmol, about 0.5 mmol, about 1 mmol, about 2 mmol, or about 3mmol to a high of about 10 mmol, about 20 mmol, about 50 mmol, about 100mmol, or about 500 mmol per mmol of titanium contained in the electrondonor-free Ziegler-Natta catalyst. For example, the concentration of thealkyl aluminum co-catalyst in the electron donor-free Ziegler-Nattacatalyst/co-catalyst mixture can range from about 0.5 mmol to about 150mmol, about 1 mmol to about 100 mmol, about 1 mmol to about 75 mmol,about 1 mmol to about 50 mmol, about 2 mmol to about 30 mmol, about 2mmol to about 20 mmol, about 3 mmol to about 15 mmol, or about 3 mmol toabout 10 mmol per mmol of titanium contained in the electron donor-freeZiegler-Natta catalyst. The concentration of the alkyl aluminumco-catalyst on a polyethylene weight basis that can be combined with theelectron donor-free Ziegler-Natta catalyst may range from about 5ppm_(w) or lower to about 200 ppm_(w) or higher, about 5 ppm_(w) toabout 150 ppm_(w), or about 10 ppm_(w) to about 150 ppm_(w).

It has been surprising and unexpectedly discovered that polyethylene andpolyethylene copolymers produced with one or more of the catalystsdiscussed and described herein have unique properties. For example, ithas been surprisingly and unexpectedly discovered that polyethylenes andcopolymers thereof produced with one or more catalysts discussed anddescribed herein can have long chain branching (LCB) and a broadmolecular weight distribution (MWD). This combination of properties isbelieved to be unique among polyethylenes produced with Ziegler-Nattacatalysts. The LCB is inherent to the granular polymer produced withinthe reactor. The LCB and the resulting melt strength and otherassociated properties are not significantly modified during thepelletization process. The combination of the broad MWD and the LCBresults in a polymer with substantially increased extrusionprocessibility and consequent reduction in pelletization costs withreduced power consumption and/or increased rate of production.

The term “polyethylene” refers to a polymer having at least 50 wt %ethylene-derived units. For example, a polyethylene can have at least 50wt % ethylene-derived units, at least 70 wt % ethylene-derived units, atleast 80 wt % ethylene-derived units, at least 90 wt % ethylene-derivedunits, at least 95 wt % ethylene-derived units, or at least 100 wt %ethylene-derived units. The polyethylene can be a homopolymer or acopolymer, including a terpolymer, having one or more other monomericunits. As such, the polyethylene can include, for example, one or moreother olefin(s) and/or alpha-olefin comonomer(s). Illustrativealpha-olefin comonomers can include, but are not limited to, thosehaving from 3 to about 20 carbon atoms, such as C₃-C₂₀ alpha-olefins,C₃-C₁₂ alpha-olefins, C₃-C₈ alpha-olefins, C₃-C₆ alpha olefins, C₃-C₅alpha olefins, C₄-C₆ alpha olefins, C₄-C₅ alpha olefins, or C₄ alphaolefins. Suitable alpha-olefin comonomers can be linear or branched orcan include two unsaturated carbon-carbon bonds (dienes). Two or morecomonomers can be used. Examples of suitable comonomers can include, butare not limited to, linear C₃-C₁₂ alpha-olefins and alpha-olefins havingone or more C₁-C₃ alkyl branches or an aryl group.

Examples of useful comonomers include propylene; 1-butene;3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with oneor more methyl, ethyl, or propyl substituents; 1-hexene; 1-hexene withone or more methyl, ethyl, or propyl substituents; 1-heptene; 1-heptenewith one or more methyl, ethyl, or propyl substituents; 1-octene;1-octene with one or more methyl, ethyl, or propyl substituents;1-nonene; 1-nonene with one or more methyl, ethyl, or propylsubstituents; ethyl, methyl, or dimethyl-substituted 1-decene;1-dodecene; and styrene; and combinations thereof. Particularlypreferred comonomers include 1-butene, 1-hexene, and 1-octene.

If one or more comonomers are used, the monomer, i.e. ethylene, can bepolymerized in a proportion of from about 50 wt % to about 99.9 wt % ofmonomer, preferably from about 70 wt % to about 99 wt % of monomer, andmore preferably, from about 80 wt % to about 98 wt % of monomer, withfrom about 0.1 wt % to about 50 wt % of the one or more comonomers,preferably from about 1 wt % to about 30 wt % of the one or morecomonomers, and more preferably from about 2 wt % to about 20 wt % ofthe one or more comonomers.

The polyethylene can have a density of about 0.900 g/cm³ to about 0.970g/cm³. For example, the polyethylene can have a density ranging from alow of about 0.910 g/cm³, about 0.915 g/cm³, about 0.920 g/cm³, or about0.925 g/cm³ to a high of about 0.940 g/cm³, about 0.945 g/cm³, about0.950 g/cm³, about 0.955 g/cm³, about 0.960 g/cm³, about 0.965 g/cm³, orabout 0.970 g/cm³. In another example, the polyethylene can have adensity of about 0.915 g/cm³ to about 0.935 g/cm³, or about 0.920 g/cm³to about 0.930 g/cm³, or about 0.935 g/cm³ to about 0.960 g/cm³, orabout 0.945 g/cm³ to about 0.957 g/cm³, or about 0.915 g/cm³ to about0.960 g/cm³, or about 0.920 g/cm³ to about 0.955 g/cm³. Density can bedetermined in accordance with ASTM D-792.

The terms “molecular weight distribution” and “MWD” mean the same thingas polydispersity index (PDI). The molecular weight distribution (MWD)is the ratio of weight-average molecular weight (Mw) to number-averagemolecular weight (Mn), i.e., Mw/Mn. The polyethylene can have amolecular weight distribution (Mw/Mn) or (MWD) ranging from about 4 toabout 14. For example, the polyethylene can have a molecular weightdistribution (Mw/Mn) ranging from a low of about 4.1, about 4.3, about4.5, about 4.7, about 4.9, about 5, about 5.5, about 6.0, about 6.5,about 6.8, about 6.9, about 7.0, or about 7.1 to a high of about 5.7,about 5.9, about 6, about 6.1, about 6.3, about 6.5, about 6.8, about7.0, about 7.3, about 7.5, about 8.0 about 9.0, about 10.0, about 11.0,about 12.0, about 13.0, or about 14.0. In another example, thepolyethylene can have a molecular weight distribution (Mw/Mn) of about4.5 to about 6.5, about 4.6 to about 6.3, about 4.9 to about 6.3, about5 to about 6.4, or about 4.5 to about 6.8. In another example, thepolyethylene can have a molecular weight distribution (Mw/Mn) of about4.5 to 14, 6.8 to 14, 6.9 to 14, or 7.0 to 14.

The polyethylene can have an Mz/Mw value of from about 3.0 to about 5.5.For example, the polyethylene can have an Mz/Mw value ranging from a lowof about 3.3, about 3.6, about 3.7, about 3.8, about 3.9, or about 4.0to a high of about 4.6, about 4.7, about 4.8, about 4.9, about 5.0, orabout 5.3. In another example, the Mz/Mw value of the polyethylene canrange from about 3.65 to about 4.85, from about 3.55 to about 4.75, fromabout 3.7 to about 4.7, or from about 3.6 to about 4.5.

Mw, Mn, and z-average molecular weight (Mz) can be measured using gelpermeation chromatography (GPC), also known as size exclusionchromatography (SEC). This technique utilizes an instrument containingcolumns packed with porous beads, an elution solvent, and detector inorder to separate polymer molecules of different sizes. Measurement ofmolecular weight by SEC is well known in the art and is discussed inmore detail in, for example, Slade, P. E. Ed., Polymer Molecular WeightsPart II, Marcel Dekker, Inc., NY, (1975) 287-368; Rodriguez, F.,Principles of Polymer Systems 3rd ed., Hemisphere Pub. Corp., NY, (1989)155-160; U.S. Pat. No. 4,540,753; and Verstrate et al., Macromolecules,vol. 21, (1988) 3360; T. Sun et al., Macromolecules, vol. 34, (2001)6812-6820.

The polyethylene can have a melt index (MI) or (I₂) ranging from about0.05 g/10 min to about 100 g/10 min. For example, the polyethylene canhave a MI (I₂) ranging from a low of about 0.10 g/10 min, about 0.4 g/10min, about 0.9 g/10 min, about 1.1 g/10 min, or about 1.5 g/10 min to ahigh of about 60 g/10 min, about 70 g/10 min, about 80 g/10 min, about90 g/10 min, or about 100 g/10 min. In another example, the polyethylenecan have a MI (I₂) of about 0.40 g/10 min to about 6 g/10 min, about 0.8g/10 min to about 3 g/10 min, about 0.3 g/10 min to about 2 g/10 min, orabout 0.4 g/10 min to about 3.5 g/10 min. In another example, thepolyethylene can have a MI (I₂) of about 0.5 g/10 min to about 45 g/10min, about 5 g/10 min to about 30 g/10 min, about 10 g/10 min to about80 g/10 min, about 40 g/10 min to about 90 g/10 min, about 1 g/10 min toabout 5 g/10 min, or about 0.05 g/10 min to about 10 g/10 min. The MI(I₂) can be measured in accordance with ASTM D-1238-E (at 190° C., 2.16kg weight).

The polyethylene can have a flow index (FI) or (I₂₁) ranging from about10 g/10 min to about 1,000 g/10 min. For example, the polyethylene canhave a FI (I₂₁) ranging from a low of about 10 g/10 min, about 15 g/10min, or about 20 g/10 min to a high of about 100 g/10 min, about 200g/10 min, about 300 g/10 min, about 400 g/10 min, or about 500 g/10 min.In another example, the polyethylene can have a FI (I₂₁) of about 30g/10 min to about 200 g/10 min, about 40 g/10 min to about 150 g/10 min,about 50 g/10 min to about 100 g/10 min, or about 100 g/10 min to about200 g/10 min. The FI (I₂₁) can be measured in accordance with ASTMD-1238-F (at 190° C., 21.6 kg weight).

The terms “melt index ratio,” “MIR,” “melt flow ratio,” “MFR,” and“I₂₁/I₂,” are used interchangeably and refer to the ratio of the flowindex (I₂₁) to melt index (I₂), The polyethylene can have a MFR (I₂₁/I₂)ranging from about 30 to about 60. For example, the polyethylene canhave a MFR ranging from about 31 to about 42, or about 32 to about 40,or about 33 to about 37, or about 34 to about 44, about 35 to about 45,about 30 to about 60, about 35 to about 55, about 45 to about 60, about46 to about 60, about 47 to about 60, about 48 to about 60, about 49 toabout 60, or about 50 to about 60. The polyethylene can have a melt flowratio (MFR) greater than or equal to 8.33+(4.17×MWD).

Various methods are known for determining the presence of long chainbranches. For example, long chain branching can be determined by using¹³C nuclear magnetic resonance (NMR) spectroscopy and to a limitedextent, e.g., for ethylene homopolymers and for certain copolymers, itcan be quantified using the method of Randall, (Journal ofMacromolecular Science: Rev. Macromol. Chem. Phys., C29 (2&3), p.285-297 (1989)). Although conventional ¹³C nuclear magnetic resonancespectroscopy can determine the length of a long chain branch for up tosix carbon atoms, when more than about six carbon atoms are present,there are other known techniques useful for quantifying or determiningthe presence of long chain branches in ethylene polymers, such asethylene/1-octene interpolymers. For those interpolymers where the ¹³Cresonances of the comonomer overlap completely with the ¹³C resonancesof the long-chain branches, either the comonomer or the other monomers(such as ethylene) can be isotopically labeled so that the long chainbranching can be distinguished from the comonomer. For example, acopolymer of ethylene and 1-octene can be prepared using ¹³C-labeledethylene. In this case, the long chain branching resonances associatedwith macromer incorporation will be significantly enhanced in intensityand will show coupling to neighboring ¹³C carbons, whereas the octeneresonances will be unenhanced. Other methods include the techniquedisclosed in U.S. Pat. No. 4,500,648, which discloses that long chainbranching frequency (LCBF) can be represented by the equationLCBF=b/M_(w), where b is the weight average number of long chainbranches per molecule and M_(w) is the weight average molecular weight.The molecular weight averages and the long chain branchingcharacteristics can be determined by gel permeation chromatography andintrinsic viscosity methods, respectively.

The polyethylene can have long chain branching (LCB). The level oramount of long chain branching refers to the number of long chainbranches per 1,000 carbon atoms. The long chain branches can have alength of 4 or greater, 5 or greater, or 6 or greater carbon atoms andup to as long as the length of the polymer back-bone. For example, thenumber of carbon atoms on the long chain branches can range from a lowof about 4, about 5, about 6, about 7, about 8, or about 9 to a high ofabout 10, about 50, about 100, about 1,000, about 10,000 or more,depending, at least in part, on the polymerization conditions. Thepolyethylene can have long chain branching (LCB) greater than about 0.01per 1,000 carbon atoms and less than about 0.07 per 1,000 carbon atoms.For example, the polyethylene can have long chain branches ranging froma low of about 0.01, about 0.015, about 0.02, about 0.025, about 0.03,about 0.04, about 0.05, about 0.055, or about 0.06 to a high of about0.035, about 0.040, about 0.045, about 0.05, about 0.06, or about 0.07per 1,000 carbon atoms.

Branches introduced as a result of comonomer incorporation, such asbranches 8 carbons long when using n-decene as a comonomer, are notconsidered “Long Chain Branches” as conventionally understood in theart. In the presence of such comonomer, LCB in the polyethylene can bedetermined by preparative temperature rising elution fractionation(pTREF), where the homopolymer or crystalline fraction eluting above 95°C. is separated from the rest of the polymer. Additional details for thepTREF technique can be as discussed and described in U.S. PatentApplication Publication No.: 2012/0028065. Using the NMR techniquesdescribed, the amount of LCB in the homopolymer fraction can bedetermined. The LCB in this fraction can be in the range 0.01 per 1000carbon atoms to 0.07 branches per 1,000 carbon atoms.

Two other useful methods for quantifying or determining the presence oflong chain branches in ethylene polymers, such as ethylene/1-octeneinterpolymers, can include gel permeation chromatography coupled with alow angle laser light scattering detector (GPC-LALLS) and gel permeationchromatography coupled with a differential viscometer detector (GPC-DV).The use of these techniques for long chain branch detection and theunderlying theories are discussed and described in the literature. See,e.g., G. H. Zimm, and W. H. Stockmayer, J. Chem. Phys., vol. 17, p. 1301(1949); and A. Rudin, “Modern Methods of Polymer Characterization,” JohnWiley & Sons, New York (1991) p. 103. Still another method fordetermining long chain branching can include GPC-FTIR as described by E.J. Markel, et al. Macromolecules, vol. 33, p. 8541 (2000).

The present disclosure allows for control of LCB in polyethylene byadjusting an amount of an alkyl aluminum co-catalyst used with anelectron donor-free Ziegler-Natta catalyst during the production of thepolyethylene. Measured values of the MFR (I₂₁/I₂) can also be used witha predetermined relationship to provide values for the LCB in thepolyethylene. The predetermined relationship between the MFR (I₂₁/I₂)and the LCB can be produced from data of both the MFR (I₂₁/I₂) and theLCB derived from varying the weight concentration of the alkyl aluminumco-catalyst in the polymerization reactor while performing thepolymerization reaction.

As discussed more below in the Examples section, FIG. 6 illustrates apredetermined relationship between the LCB for otherwise linear lowdensity polyethylene (LLDPE) polymers versus the concentration of alkylaluminum co-catalyst (e.g., TEAl) used in forming the polymers. Theexamples provided in FIG. 6 and the following figures (e.g., FIGS. 6-13)are for LCB resulting from the use of butene monomers, where the LCB isdefined as greater than or equal to (≧) four (4) carbons in length. FIG.10 illustrates a predetermined relationship between the LCB for highdensity polyethylene (HDPE) polymers versus the concentration ofco-catalyst (TEAl) used in forming the polymers. As seen in FIGS. 6 and10, as the concentration of the TEAl co-catalyst decreases (given inppm_(w)—parts per million weight) the LCB for the polyethylene polymerincreases. FIGS. 7 and 11 illustrate a graphical representation of thepolymer MFR (I₂₁/I₂) versus the concentration of co-catalyst (TEAl) forthe polyethylene polymers where it is seen that as the concentration ofthe TEAl co-catalyst decreases the MFR for the polyethylene polymerincreases. The same trend is repeated with the association between theelectron donor-free Ziegler-Natta catalyst productivity versus theconcentration of co-catalyst (TEAl) in the polyethylene polymers, asseen in FIGS. 8 and 12. Using these surprising results it is thenpossible to provide the predetermined relationship between the LCBversus the polymer MFR (I₂₁/I₂) for the polyethylene polymer, as seen inFIGS. 9 and 13.

As mentioned, measured values of the MFR (I₂₁/I₂) are used with apredetermined relationship to provide values for the LCB in thepolyethylene. Based on the data discussed above (data of both the MFR(I₂₁/I₂) and the LCB derived from varying the weight concentration ofthe alkyl aluminum co-catalyst in the polymerization reactor whileperforming the polymerization reaction) and provided in the Examplessection herein, the predetermined relationship between the MFR (I₂₁/I₂)and the LCB (≧C4 Branch/1000 C) provides that for LDPE the predeterminedrelationship is:

LCB=3.3514×10⁻⁶×(LDPE Polymer MFR)³−5.0204×10⁻⁴×(LDPE PolymerMFR)²+0.025348×(LDPE Polymer MFR)−0.3749

For HDPE the predetermined relationship is:

LCB=0.0022×(HDPE Polymer MFR)−0.0415

The LDPE equation for LCB best applies over a range of about 30 MFR toabout 60 MFR. The HDPE equation for LCB best applies over a range ofabout 35 MFR to about 50 MFR.

The measured values for the electron donor-free Ziegler-Natta catalystproductivity of the polyethylene from the polymerization reactor canalso be used to determine the amount of LCB of the polyethylene from thepolymerization reactor using a measurement of the electron donor-freeZiegler-Natta catalyst productivity with a predetermined relationshipbetween the electron donor-free Ziegler-Natta catalyst productivity andthe LCB, as mentioned herein. This predetermined relationship betweenthe electron donor-free Ziegler-Natta catalyst productivity and the LCBcan take the form of a linear equation, as seen below. As illustratedbelow, a first of the predetermined relationships is for the productionof the LDPE (based on data provided in the Examples section herein andillustrated in FIG. 14) and a second of the predetermined relationshipsis for the production of the HDPE (based on data provided in theExamples section herein and illustrated in FIG. 15):

LCB=0.99×10⁻⁶×(LDPE Catalyst Productivity)+0.0394

LCB=9.15×10⁻⁶×(HDPE Catalyst Productivity)−0.0048

For the above equations, the preferred range for the predeterminedrelationship for LDPE catalyst productivity is from about 4,000 lb/lb toabout 20,000 lb/lb, where the preferred range for the predeterminedrelationship for HDPE catalyst productivity is from about 4,500 lb/lb toabout 7,500 lb/lb.

The catalyst productivity provided in these equations is measured byInductively Coupled Plasma Emission Spectroscopy (ICPES). Alternatively,the catalyst productivity can be determined from a material balancearound the polymerization reactor based on the weight amount of polymerdischarged from the reactor divided by the weight amount of catalyst fedto the reactor.

Using the predetemined equations provided herein, changes in catalystproductivity (particularly the catalyst productivity based on reactormaterial balance that can be calculated instantly) and/or MFR values canbe used to make essentially real time changes in the co-catalyst feedrate to the polymerization reactor. This may allow for control of thecatalyst productivity at its desired level before the MFR deviates ordeviates greatly from its target value. The LCB can likewise becontrolled, adjusted and/or maintained at its desired level. Thematerial balance catalyst productivity is thus a leading indicator ofimpending changes in polymer composition, which allows for control inreal time of the polymerization process. An LCB control model based onmaterial balance productivity (material balance around the reactorincluding the catalyst feed rate and the polymer production rate) mayalso be developed incorporating the LCB parameters and equationsprovided herein. This model may provide excellent instant indication ofthe catalyst productivity and the LCB of the polymer being produced.

So, the LCB relates to the MFR and to the catalyst productivity, whereeach of these properties can be related back to the alkyl aluminumco-catalyst concentration used in producing the polymer in apredetermined relationship. Using this predetermined relationship, theamount of LCB of the polyethylene can be determined from thepolymerization reactor using the measured MFR (I₂₁/I₂) and/or catalystproductivity. Measurable parameters such as the MFR and/or productivitycan then be used in essentially real time during polymer production asan indication of the LCB for the polymer. This relationship can thenlead to better process control of the polymerization process, where anamount of the LCB can be controlled and/or adjusted by controlling theMFR and/or catalyst productivity through control of and/or changes tothe amount of alkyl aluminum co-catalyst (e.g., TEAl) in thepolymerization reactor.

The predetermined relationships provided herein can be used inpolymerization process control methods for making polyethylene in whichthe LCB in the polyethylene can be controlled by adjusting an amount ofthe alkyl aluminum co-catalyst used with an electron donor-freeZiegler-Natta catalyst during the production of the polyethylene. Suchprocess control methods include performing the polymerization reactionis a polymerization reactor to produce the polyethylene, where ethylene,and optionally one or more comonomers in the polymerization reaction iscatalyzed by the electron donor-free Ziegler-Natta catalyst and thealkyl aluminum co-catalyst. As seen from the data discussed herein,adjusting the concentration of the alkyl aluminum co-catalyst allows forthe manipulation and control of the electron donor-free Ziegler-Nattacatalyst productivity and the MFR (I₂₁/I₂) of the polyethylene.Surprisingly, the amount of LCB in the polyethylene can be controlled bythe concentration of alkyl aluminum co-catalyst used in thepolymerization process.

Process control during the production of the polyethylene can also beaccomplished using the MFR and/or the electron donor-free Ziegler-Nattacatalyst productivity, where these measureable parameters can be used asindicators of the instant LCB when LCB measurements cannot be madeduring the polymerization reaction. One approach to this process controlcan include adjusting the weight concentration of the alkyl aluminumco-catalyst present in the polymerization reactor and/or the alkylaluminum co-catalyst to Ziegler-Natta active metal molar ratio tocontrol the amount of LCB in the polyethylene polymer. As seen in thedata discussed above, changes in the concentration of the alkyl aluminumco-catalyst can lead to changes in the electron donor-free Ziegler-Nattacatalyst productivity and the MFR of the polyethylene. For example, asthe concentration of the alkyl aluminum co-catalyst is reduced for agiven polymerization process, the electron donor-free Ziegler-Nattacatalyst productivity and the MFR of the polyethylene both increase.

During polyethylene production, the weight concentration of the alkylaluminum co-catalyst in the polymerization reactor can be adjusted so asto bring the LCB in the polyethylene into compliance with apredetermined product specification set for the desired polyethylene.Examples of suitable polymerization reactors for the present disclosureinclude those selected from the group consisting of a solution reactor,a slurry loop reactor, a supercritical loop reactor, a stirred gas-phasereactor, or a fluidized-bed gas-phase reactor.

Changes to the weight concentration of the alkyl aluminum co-catalystcan be accomplished in a variety of ways. For example, a weightconcentration of the electron donor-free Ziegler-Natta catalyst can bereduced when the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor is reduced. A weight concentrationof the electron donor-free Ziegler-Natta catalyst can also be increasedto maintain a constant production rate of the polyethylene when theweight concentration of the alkyl aluminum co-catalyst present in thepolymerization reactor is increased. Adjusting the weight concentrationof the alkyl aluminum co-catalyst present in the polymerization reactorcan also be accomplished by changing a mole ratio of the alkyl aluminumco-catalyst to active metal in the electron donor-free Ziegler-Nattacatalyst. In an additional embodiment, deviations in the catalystproductivity can function as a leading indicator of impending changes inthe polymer MFR and/or LCB. This leading indicator of impending changesis then used by responding to the deviations in catalyst productivity byadjusting the weight concentration of the alkyl aluminum co-catalyst inthe polymerization reactor whereby the electron donor-free Ziegler-Nattacatalyst productivity of the polyethylene from the polymerizationreactor is controlled. In addition, deviations in the catalystproductivity functioning as the leading indicator of impending changesin the polymer MFR and/or LCB can also be used in responding to thedeviations in catalyst productivity by adjusting a feed rate of theelectron donor-free Ziegler-Natta catalyst whereby a constantpolyethylene production rate from the polymerization reactor ismaintained that corresponds to a change in the catalyst productivity.The concentration of the alkyl aluminum co-catalyst in thepolymerization reactor may then be adjusted based on the new calculatedcatalyst productivity. The weight concentration of the alkyl aluminumco-catalyst in the polymerization reactor, for example, can also bedecreased to allow for an increase in productivity of the electrondonor-free Ziegler-Natta catalyst relative to the productivity beforethe change in weight concentration.

As discussed herein, adjusting the weight concentration of the alkylaluminum co-catalyst present in the polymerization reactor can alsocause a variety of changes in the physical properties of thepolyethylene produced in the polymerization reactor. For example,adjusting the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor can cause changes in the MFR(I₂₁/I₂) of the polyethylene from the polymerization reactor. Adjustingthe weight concentration of the alkyl aluminum co-catalyst present inthe polymerization reactor may also change a production rate of thepolyethylene from the polymerization reactor. Adjustments to the weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor may also change cycle gas molar ratios of eitherH₂/C₂ and C₄/C₂ and/or H₂/C₂ and C₆/C₂. The MFR (I₂₁/I₂) of thepolyethylene from the polymerization reactor may also be controlled byadjusting one or more of a H₂/C₂ gas mole ratio, H₂/C₂ weight feedratio, a C₄ to C₂ co-monomer gas mole ratio or the C₄ to C₂ weight feedratio. Similarly, the MFR (I₂₁/I₂) of the polyethylene from thepolymerization reactor may also be controlled by adjusting one or moreof a C₆/C₂ gas mole ratio, C₆/C₂ weight feed ratio, a C₆ to C₂co-monomer gas mole ratio or the C₆ to C₂ weight feed ratio.

Comonomer distribution analysis can be performed with CrystallizationElution Fractionation (CEF) (Monrabal, B. et al., Macromol. Symp., 257,p. 71 (2007)). Ortho-dichlorobenzene (ODCB) with 600 ppm antioxidantbutylated hydroxytoluene (BHT) can be used as solvent. Samplepreparation can be done with an autosampler at 160° C. for about 2 hoursunder shaking at 4 mg/ml (unless otherwise specified). The injectionvolume can be about 300 μl. The temperature profile of CEF is:crystallization at 3° C./min from 110° C. to 30° C., the thermalequilibrium at 30° C. for 5 minutes, elution at 3° C./min from 30° C. to140° C. The flow rate during crystallization can be at 0.052 ml/min. Theflow rate during elution can be at 0.50 ml/min. The data can becollected at one data point/second. The glass beads can be acid washedand the CEF column can be packed with glass beads at 125 μm±6% (MO-SCISpecialty Products) with 0.125 inch stainless steel tubing. The columnvolume can be about 2.06 ml. The column temperature calibration can beperformed using a mixture of NIST Standard Reference Material Linearpolyethylene 1475a (1.0 mg/ml) and Eicosane (2 mg/ml) in ODCB. Thetemperature can be calibrated by adjusting elution heating rate so thatNIST linear polyethylene 1475a has a peak temperature at 101° C., andEicosane has a peak temperature at 30.0° C. The CEF column resolutioncan be calculated with a mixture of NIST linear polyethylene 1475a (1.0mg/ml) and hexacontane (Fluka, purum, >97.0%, 1 mg/ml). A baselineseparation of hexacontane and NIST polyethylene 1475a can be achieved.The area of hexacontane (from 35.0° C. to 67.0° C.) to the area of NIST1475a from 67.0° C. to 110.0° C. can be 50 to 50, the amount of solublefraction below 35.0° C. can be less than 1.8 wt %. The column resolutioncan be 6.0. The CEF column resolution can be defined as:

${Resolution} = \frac{\begin{matrix}{{{peak}\mspace{14mu} {temperature}\mspace{14mu} {of}\mspace{14mu} {NIST}\mspace{14mu} 1475\; a} -} \\{{peak}\mspace{14mu} {temperature}\mspace{14mu} {of}\mspace{14mu} {hexacontrane}}\end{matrix}}{\begin{matrix}{{{half}\text{-}{height}\mspace{14mu} {width}\mspace{14mu} {of}{\mspace{11mu} \;}{NIST}\mspace{14mu} 1475\; a} +} \\{{half}\text{-}{height}\mspace{14mu} {width}\mspace{14mu} {of}{\mspace{11mu} \;}{hexacontrane}}\end{matrix}}$

The polyethylene can have a heterogeneous distribution of short chainbranching (SCB). As used herein, the terms “heterogeneous branchingdistribution,” “heterogeneously branched,” and “heterogeneousdistribution of short chain branching” are used interchangeably andrefer to: (1) molecules of different chain length contain differentlevels of comonomer and in particular the molecules of lower chainlength contain higher amounts of comonomer i.e., a lower ethylene tocomonomer ratio, (2) the polymer is characterized by a broad short chainbranching distribution where the comonomer heterogeneity index or (CHI)is <0.5, and (3) the polymer contains a measureable high density(crystalline) fraction shown as a peak at an elution temperature ofabout 100° C. in any of several known fractionation techniques thatinvolve polymer fractional elution as a function of temperature, e.g.,temperature rising elution fractionation (TREF) (see, e.g., U.S. Pat.No. 5,008,204 and J. Wild et al., Poly. Sci., Poly. Phy. Ed., vol. 20,p. 441 (1982)), crystallization analysis fractionation (CRYSTAF) (see,e.g., D. Beigzadeh, J. B. P. Soares, and T. A. Duever; “Modeling ofFractionation in CRYSTAF Using Monte Carlo Simulation of CrystallizableSequence Lengths: Ethylene/1-octene Copolymers Synthesized withSingle-Site-Type Catalysts,” J. Applied Polymer Science, vol. 80, No.12, p. 2200 (2001); also B. Morabal, J. Blanco, J. Nieto, and J. B. P.Soares, Polym. Sci Part A: Polym. Chem., vol. 37, p. 89 (1999)), andcrystallization elution fraction (CEF), which is discussed and describedin WO Publication No. WO2011/002868. The polyethylene can have acomonomer heterogeneity index (CHI) of less 0.5, less than about 0.47,less than about 0.45, less than about 0.43, less than about 0.40, lessthan about 0.37, less than about 0.35, less than about 0.33, less thanabout 0.3, less than about 0.27, less than about 0.25, less than about0.23, or less than about 0.20.

The compounds were measured for melt strength by Rheotens at 190° C. andby dynamic EVF using an ARES Melt rheometer. The terms “melt strength”and “MS” are used interchangeably and refer to the maximum tensile forcemeasured on a molten filament of a polymer melt extruded from acapillary rheometer die at a constant shear rate of 33 reciprocalseconds (sec⁻¹) while the filament is being stretched by a pair of niprollers that are accelerating the filament at a rate of about 0.24centimeters per second per second (cm/sec²) from an initial speed ofabout 1 cm/sec. The maximum force can be determined from the Forceversus take off velocity data as follows: in the absence of drawresonance, the melt strength value is the maximum value immediatelybefore break; in the presence of draw resonance before break, the meltstrength is the average value of twenty data points before the onset ofdraw resonance, where draw resonance is defined as an oscillation thathas an amplitude greater than 10% of the mean value of the oscillation.The molten filament is preferably generated by heating about 10 g of apolymer that is packed into a barrel of an Instron capillary rheometer,equilibrating the polymer at 190° C. for five minutes, and thenextruding the polymer at a piston speed of about 2.54 cm/minute (cm/min)through a capillary die with a diameter of about 0.21 cm and a length ofabout 4.19 cm. The tensile force is preferably measured with a GoettfertRheotens that is located so that the nip rollers are about 10 cmdirectly below a point at which the filament exits the capillary die.

The melt strength of the polyethylene can also be represented in theform of an equation. More particularly, the melt strength of thepolyethylene can be represented by the equation: meltstrength≈7.6938×exp(−1.56×log(MI)), where the logarithm is base 10. Inone or more embodiments, the polyethylene can have a density greaterthan or equal to 0.945 g/cm³ and a melt strength greater than or equalto a×(3.7463×exp(−1.485×log(MI))), where a is equal to 1.5, 1.55, 1.6,1.65, 1.7, 1.75, 1.8, 1.85, or 1.9. For example, a heterogeneouspolyethylene can have a density greater than or equal to 0.945 g/cm³ anda melt strength greater than or equal to a×(3.7463×exp(−1.485×log(MI))),where a is equal to 1.5, 1.75, or 1.9. In one or more embodiments, thepolyethylene can have a density less than 0.945 g/cm³ and a meltstrength greater than or equal to a×(3.7463×exp(−1.485×log(MI))), wherea is equal to 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65,1.7, 1.75, 1.8, 1.85, or 1.9. For example, a heterogeneous polyethylenecan have a density less than 0.945 g/cm³ and a melt strength greaterthan or equal to a×(3.7463×exp(−1.485×log(MI))), where a is equal to1.2, 1.5, or 1.9.

The polyethylene can have a melt strength ranging from a low of about 2centi-Newtons (cN), about 3 cN, about 3.5 cN, about 4 cN, or about 4.5cN to a high of about 6 cN, about 8 cN, about 10 cN, about 12 cN, about14 cN, about 16 cN, about 18 cN, or about 20 cN. For example, thepolyethylene can have a melt strength of about 2 cN to about 7 cN, about2.5 cN to about 6 cN, about 3.3 cN to about 7.3 cN, about 3.6 cN toabout 7 cN, or about 2.2 cN to about 6.8 cN. In another example, thepolyethylene can have a melt strength of about 3.3 cN to about 16 cN,about 5 cN to about 18 cN, about 6 cN to about 14 cN, about 8 cN toabout 20 cN, or about 8.5 cN to about 17 cN. In another example, thepolyethylene can have a melt strength of at least 2 cN, at least 3 cN,at least 4 cN, at least 5 cN, at least 6 cN, at least 7 cN, at least 8cN, at least 9 cN, at least 10 cN, at least 11 cN, at least 12 cN, atleast 13 cN, at least 14 cN, at least 15 cN, or at least 16 cN. Inanother example, the polyethylene can have a melt strength of at least2.5 cN, at least 3.5 cN, at least 4.5 cN, at least 5.5 cN, at least 6.5cN, at least 7.5 cN, at least 8.5 cN, at least 9.5 cN, at least 10.5 cN,at least 11.5 cN, at least 12.5 cN, at least 13.5 cN, at least 14.5 cN,at least 15.5 cN, or at least 16.5 cN.

The polyethylene can have a slope of strain hardening (SSH) greater thanabout 0.75, greater than about 0.80, greater than about 0.85, greaterthan about 0.90, greater than about 0.95, or greater than about 1.00, asmeasured by extensional viscosity fixture (EVF). For example, thepolyethylene can have a SSH ranging from a low of about 0.76, about0.78, about 0.80, about 0.83, about 0.85, or about 0.87 to a high ofabout 0.90, about 0.95, about 1.00, about 1.10, about 1.20, about 1.30,or about 1.40, as measured by EVF. For example, the polyethylene canhave a slope of strain hardening greater than about 0.75 to about 1.35,about 0.80 to about 1.30, about 0.90 to about 1.29, about 0.95 to about1.35, about 1.00 to about 1.35, or about 1.05 to about 1.30, as measuredby EVF.

The extensional viscosity can be measured by an extensional viscosityfixture (EVF) of TA Instruments (New Castle, Del.) attached onto an ARESrheometer of TA Instruments at Hencky strain rates of 10 s⁻¹, 1 s⁻¹, and0.1 s⁻¹ at 150° C. A sample plaque can be prepared on a programmableTetrahedron bench top press. The program can hold the melt at 177° C. ata pressure of 1,500 psi (10⁷ Pa) for 5 minutes. The chase is thenremoved to the bench top to cool. The test samples can be die-cut fromthe sample plaque using a punch press and a handheld die with thedimensions of about 10 mm×18 mm (Width×Length). The specimen thicknesscan range from about 0.7 mm to about 1.1 mm.

The TA instruments Extensional Velocity Fixture (EVF) can be used with aconventional Aries rheometer. The rheometer oven that encloses the EVFfixture can be set to a test temperature of about 150° C. for at least60 minutes prior to zeroing fixtures. The width and thickness of eachsample film can be measured at three different locations of the plaquesample and the average values can be entered into the test program (TAOrchestrator version 7.2). Densities of the sample at room temperatureand at the test temperature (0.78 g/cm³) can also be entered into thetest program to allow for the program to calculate the actual dimensionsof the sample film at the test temperature. The density of the sample atroom temperature varies from sample to sample and the density measuredaccording to ASTM D-792 can be used. The film specimen can be attachedonto each of the two drums of the fixture by a pin. The oven can beclosed to let the temperature equilibrate before starting the test. Thetest was divided into three zones. The first zone is the pre-stretchzone that stretches the film at a strain rate of about 0.005 s⁻¹ for 11seconds. Pre-stretching the film can reduce the film buckling introducedwhen the film is loaded. This is followed by a relaxation zone of about60 seconds to minimize or reduce the stress introduced in thepre-stretch step. The third zone is the measurement zone where the filmis stretched at the pre-set Hencky strain rate. The data collected inthe third zone is that used for analysis.

The extensional viscosity can be measured at about 150° C. Data for thecalculation of slope of strain hardening can be collected at a strainrate of about 0.1 s⁻¹. The slope of strain hardening SSH can becalculated as follows: (a) data is recorded as viscosity (Pa·s) vs.elapsed time (seconds), (b) viscosity increases with elapsed time; datain the range of elapsed time >1 sec is considered for the purposes ofthis calculation, (c) the point immediately before breakage, or adecrease in viscosity, or an obvious slippage of the sample signified bya sudden rise or fall in force is noted: value F_(max) and time t_(max);the log of t_(max) is calculated=Lt_(max), (d) with time expressed aslog₁₀(time), the range of data to be used for the calculation is between0.9×Lt_(max) and 0.75×Lt_(max) (the point adjacent and less than0.9×Lt_(max) and the point adjacent to and greater than 0.75×Lt_(max)define the upper and lower limits of the range), (e) using the range ofstep (d), the data are plotted as log(viscosity) vs. log(time), (f)using conventional linear regression techniques known in the art, a lineof the form y=m×x+c is fitted to the data (the linear line fit offeredin Microsoft Corporation's EXCEL® program is suitable, (g) the slope ofstrain hardening is equal to m. Since the slope is measured in logspace, the slope of strain hardening value (SSH) is a dimensionlessnumber. Additional information with regard to extensional viscosity canbe found in J. Chem. Educ., vol. 74, No. 8, p. 899 (1997); and J. Chem.Educ., vol. 72, No. 10, p. 954 (1995).

The electron donor-free Ziegler-Natta catalyst can be used to polymerizeone or more olefins to provide one or more polymer products therefrom.Any polymerization process including, but not limited to, high pressure,solution, slurry, and/or gas phase processes can be used. Preferably, acontinuous gas phase process utilizing a fluidized bed reactor is usedto polymerize ethylene or ethylene and one or more comonomers to providea polyethylene or a polyethylene copolymer, respectively. The comonomerscan be as discussed and described above.

An illustrative fluidized bed reactor can include a reaction zone and aso-called velocity reduction zone. The reaction zone can include a bedof growing polymer particles, formed polymer particles and a minoramount of catalyst particles fluidized by the continuous flow of thegaseous monomer and diluent to remove heat of polymerization through thereaction zone. Optionally, some of the re-circulated gases may be cooledand compressed to form liquids that increase the heat removal capacityof the circulating gas stream when readmitted to the reaction zone. Asuitable rate of gas flow may be readily determined by simpleexperiment. Make up of gaseous monomer to the circulating gas stream canbe at a rate equal to the rate at which particulate polymer product andmonomer associated therewith can be withdrawn from the reactor and thecomposition of the gas passing through the reactor can be adjusted tomaintain an essentially steady state gaseous composition within thereaction zone. The gas leaving the reaction zone can be passed to thevelocity reduction zone where entrained particles are removed. Finerentrained particles and dust may be removed in a cyclone and/or finefilter. The gas can be passed through a heat exchanger where the heat ofpolymerization can be removed, compressed in a compressor, and thenreturned to the reaction zone. Additional reactor details and means foroperating the reactor are described in, for example, U.S. Pat. Nos.3,709,853; 4,003,712; 4,011,382; 4,302,566; 4,543,399; 4,882,400;5,352,749; and 5,541,270; EP 0802202; and Belgian Patent No. 839,380.

The reactor temperature of the fluid bed process can range from 30° C.or 40° C. or 50° C. to 90° C. or 100° C. or 110° C. or 120° C. Ingeneral, the reactor temperature can be operated at the highesttemperature that can be feasible taking into account the sinteringtemperature of the polyethylene within the reactor. Regardless of theprocess used to make the polyethylene, the polymerization temperature orreaction temperature should be below the melting or “sintering”temperature of the polyethylene to be formed. Thus, the uppertemperature limit in one embodiment is the melting temperature of thepolyethylene produced in the reactor.

Hydrogen gas can be used in olefin polymerization to control the finalproperties of the polyolefin, such as described in “PolypropyleneHandbook,” at pages 76-78 (Hanser Publishers, 1996). Increasingconcentrations (partial pressures) of hydrogen can increase the meltindex (MI) of the polyethylene generated. The MI can thus be influencedby the hydrogen concentration. The amount of hydrogen in thepolymerization reactor can be expressed as a mole ratio relative to thetotal polymerizable monomer, for example, ethylene, or a blend ofethylene and hexene. The amount of hydrogen used in the polymerizationprocess can be an amount sufficient to achieve the desired MI of thefinal polyolefin resin. In one embodiment, the mole ratio of hydrogen tototal monomer (H₂/C₂) can be in a range from greater than 0.0001 in oneembodiment, and from greater than 0.0005 in another embodiment, and fromgreater than 0.001 in yet another embodiment, and less than 10 in yetanother embodiment, and less than 5 in yet another embodiment, and lessthan 3 in yet another embodiment, and less than 0.10 in yet anotherembodiment, wherein a desirable range can include any combination of anyupper mole ratio limit with any lower mole ratio limit described herein.Expressed another way, the amount of hydrogen in the reactor at any timemay range to up to 5,000 ppm_(v), and up to 4,000 ppm_(v) in anotherembodiment, and up to 3,000 ppm_(v) in yet another embodiment, andbetween 50 ppm_(v) and 5,000 ppm_(v) in yet another embodiment, andbetween 500 ppm_(v) and 2,000 ppm_(v) in another embodiment.

The amount of hydrogen may also be expressed as the weight feed ratiorelative to the ethylene feed. For control of melt index it is necessaryto adjust the level of hydrogen either as gas mole ratio or the feedratio.

The one or more reactor pressures in a gas phase process (either singlestage or two or more stages) may vary from 690 kPa to 3,448 kPa, and inthe range from 1,379 kPa to 2,759 kPa in another embodiment, and in therange from 1,724 kPa to 2,414 kPa in yet another embodiment.

The gas phase reactor can be capable of producing from 227 kg of polymerper hour (kg/hr) to 90,900 kg/hr, and greater than 455 kg/hr in anotherembodiment, and greater than 4,540 kg/hr in yet another embodiment, andgreater than 11,300 kg/hr in yet another embodiment, and greater than15,900 kg/hr in yet another embodiment, and greater than 22,700 kg/hr inyet another embodiment, and from 29,000 kg/hr to 45,500 kg/hr in yetanother embodiment.

In one or more embodiments, a staged reactor employing two or morereactors in series, where one reactor may produce, for example, a highmolecular weight component and another reactor may produce a lowmolecular weight component can be used. In one or more embodiments, thepolyolefin can be produced using a staged gas phase reactor. Suchcommercial polymerization systems are described in, for example, “Volume2, Metallocene-Based Polyolefins,” at pages 366-378 (John Scheirs & W.Kaminsky, eds. John Wiley & Sons, Ltd. 2000); U.S. Pat. Nos. 5,665,818;5,677,375; and 6,472,484; and EP 0 517 868 and EP 0 794 200.

A slurry polymerization process can also be used. A slurrypolymerization process generally uses pressures in the range of fromabout 101 kPa to about 5,070 kPa and even greater and temperatures inthe range of from about 0° C. to about 120° C., and more particularlyfrom about 30° C. to about 100° C. In a slurry polymerization, asuspension of solid, particulate polymer can be formed in a liquidpolymerization diluent medium to which ethylene and comonomers and oftenhydrogen along with catalyst are added. The suspension including diluentcan be intermittently or continuously removed from the reactor where thevolatile components are separated from the polymer and recycled,optionally after a distillation, to the reactor. The liquid diluentemployed in the polymerization medium can be an alkane having from 3 to7 carbon atoms, such as, for example, a branched alkane. The mediumemployed should be liquid under the conditions of polymerization andrelatively inert. When a propane medium can be used the process must beoperated above the reaction diluent critical temperature and pressure.In one embodiment, a hexane, isopentane, or isobutane medium can beemployed.

One or more co-catalysts, if used, can be combined with the electrondonor-free Ziegler-Natta catalyst outside of the polymerization reactor,within the polymerization reactor, or a combination thereof. Forexample, the electron donor-free Ziegler-Natta catalyst and theco-catalyst can be separately introduced to the polymerization reactorand combined therein. In another example, the electron donor-freeZiegler-Natta catalyst and the co-catalyst can be combined with oneanother outside or external to the polymerization reactor and introducedas a mixture to the polymerization reactor. In another example, a firstportion of the co-catalyst can be combined with the electron donor-freeZiegler-Natta catalyst external the polymerization reactor and a secondportion of the co-catalyst can be combined with the mixture of the firstportion of the co-catalyst and the electron donor-free Ziegler-Nattacatalyst within the polymerization reactor. The co-catalyst can be usedin high pressure, solution, slurry, and/or gas phase polymerizationprocesses.

It has been surprisingly and unexpectedly discovered that the inventivecatalyst compositions discussed and described herein may producepolyethylene and polyethylene copolymers with increased efficiency andmelt flow ratios (I₂₁/I₂) when lesser amounts of co-catalyst areemployed. Said another way, decreasing the co-catalyst to catalyst ratiomay allow for increased catalyst productivity (typically described aspounds of resin produced per pound of catalyst) as well as increasedmelt flow ratios of the polyethylene or polyethylene copolymersproduced. As such in preferred embodiments the concentration ofco-catalyst in the co-catalyst/catalyst mixture may be less than about20 mmol co-catalyst per mmol titanium contained in the electrondonor-free Ziegler-Natta catalyst, or less than about 10 mmolco-catalyst per mmol titanium contained in the electron donor-freeZiegler-Natta catalyst, or less than about 5 mmol co-catalyst per mmoltitanium contained in the electron donor-free Ziegler-Natta catalyst.

In polymerization processes disclosed herein, it may also be desired toadditionally use one or more static control agents to aid in regulatingstatic levels in the reactor. As used herein, a static control agent isa chemical composition which, when introduced into a fluidized bedreactor, may influence or drive the static charge (negatively,positively, or to zero) in the fluidized bed. The specific staticcontrol agent used may depend upon the nature of the static charge, andthe choice of static control agent may vary dependening upon the polymerbeing produced and the electron donor-free Ziegler-Natta catalystcompound(s) being used. For example, the use of static control agents isdisclosed in European Patent No. 0229368 and U.S. Pat. Nos. 4,803,251;4,555,370; and 5,283,278, and references cited therein.

Control agents such as aluminum stearate may also be employed. Thestatic control agent used may be selected for its ability to receive thestatic charge in the fluidized bed without adversely affectingproductivity. Other suitable static control agents may also includealuminum distearate, ethoxlated amines, and anti-static compositionssuch as those provided by Innospec Inc. under the trade name OCTASTAT.For example, OCTASTAT™ 2000 is a mixture of a polysulfone copolymer, apolymeric polyamine, and oil-soluble sulfonic acid.

Any of the aforementioned control agents, as well as those described in,for example, WO 01/44322, listed under the heading Carboxylate MetalSalt and including those chemicals and compositions listed as antistaticagents may be employed either alone or in combination as a controlagent. For example, the carboxylate metal salt may be combined with anamine containing control agent (e.g., a carboxylate metal salt with anyfamily member belonging to the KEMAMINE™ (available from CromptonCorporation) or ATMER™ (available from ICI Americas Inc.) family ofproducts).

Other useful continuity additives include, ethyleneimine additivesuseful in embodiments disclosed herein may include polyethyleneimineshaving the following general formula:

—(CH₂—CH₂—NH)_(n)—

where n can be from about 10 to about 10,000. The polyethyleneimines maybe linear, branched, or hyperbranched (i.e., forming dendritic orarborescent polymer structures). They can be a homopolymer or copolymerof ethyleneimine or mixtures thereof (referred to aspolyethyleneimine(s) hereafter). Although linear polymers represented bythe chemical formula —[CH₂ CH₂ NH]— may be used as thepolyethyleneimine, materials having primary, secondary, and tertiarybranches can also be used. Commercial polyethyleneimine can be acompound having branches of the ethyleneimine polymer. Suitablepolyethyleneimines are commercially available from BASF Corporationunder the trade name Lupasol. These compounds can be prepared as a widerange of molecular weights and product activities. Examples ofcommercial polyethyleneimines sold by BASF suitable for use in thepresent invention include, but are not limited to, Lupasol™ FG andLupasol™ WF. Another useful continuity additive can include a mixture ofaluminum distearate and an ethoxylated amine type compound, e.g.,IRGASTAT™ AS-990, available from Huntsman (formerly Ciba SpecialtyChemicals). The mixture of aluminum distearate and ethoxylated aminetype compound can be slurried in mineral oil e.g., Hydrobrite 380. Forexample, the mixture of aluminum distearate and an ethoxylated aminetype compound can be slurried in mineral oil to have total slurryconcentration ranging from about 5 wt % to about 50 wt % or about 10 wt% to about 40 wt %, or about 15 wt % to about 30 wt %. Other usefulstatic control agents and additives are disclosed in U.S. PatentApplication Publication No. 2008/0045663.

The continuity additive(s) or static control agent(s) may be added tothe reactor in an amount ranging from 0.05 to 200 ppm, based on theweight of all feeds to the reactor, excluding recycle, more preferablyin an amount ranging from 2 to 100 ppm; more preferably from 4 to 50 ppmin yet other embodiments.

As discussed above, conventional polyethylenes produced fromZiegler-Natta catalyzed polyethylenes may be, and often are, blendedwith high pressure low density polyethylenes (LDPE) in an attempt tocombine the processibility of the low density polyethylene and thephysical attributes of the Ziegler-Natta catalyzed polyethylene. It hasbeen surprisingly and unexpectedly discovered that the Ziegler-Nattacatalyzed polyethylenes discussed and described herein can avoid theneed or substantially reduce the need for blending LDPE and/or otherpolymers therewith in order to obtain acceptable processibility. Inother words, the polyethylenes discussed and described herein can beused alone or can be blended with one or more additional polymers if sodesired. Other suitable polymers that can be blended with thepolyethylenes discussed and described herein can include, but are notlimited to, high pressure low density polyethylene (LDPE), ethylenevinyl acetate, ethylene ethylacrylate, ethylene acrylic acid,ethylene-styrene interpolymers, polyethylene homopolymers,ethylene/alpha-olefin copolymers made with conventional catalysts andprocesses known in the art, and the like, or any combination thereof.

A polymer blend containing the polyethylene and one or more otherpolymers, e.g., LDPE, can be formed using conventional equipment andmethods, such as by dry blending the individual components andsubsequently melt mixing in a mixer or by mixing the components togetherdirectly in a mixer, such as, for example, a Banbury mixer, a Haakemixer, a Brabender internal mixer, or a single or twin-screw extruder,which can include a compounding extruder and a side-arm extruder useddirectly downstream of a polymerization process. In another example, thepolymer blend can be produced in situ using a multistage polymerizationreactor arrangement and process. In a multistage reactor arrangement twoor more reactors can be connected in series where a mixture of a firstpolymer, e.g., the polyethylene and catalyst precursor can betransferred from a first reactor to a second reactor where a secondpolymer, e.g., a metallocene catalyzed polyethylene, can be produced andblended in situ with the first polymer.

A polymer blend that includes the polyethylene can include at least 0.1percent by weight (wt %) and up to 99.9 wt % of the polyethylene and atleast 0.1 wt % and up to 99.9 wt % of the one or more other polymers,based on the combined weight of the polyethylene and the one or moreother polymers. For example, the amount of the polyethylene in thepolymer blend can range from a low of about 55 wt %, about 60 wt %,about 65 wt %, about 70 wt %, or about 75 wt % to a high of about 80 wt%, about 85 wt %, about 90 wt %, about 95 wt %, or about 99 wt %, basedon the combined weight of the polyethylene and the one or more otherpolymers. In another example, the amount of the polyethylene in thepolymer blend can range from about 60 wt % to about 85 wt %, about 75 wt% to about 95 wt %, about 80 wt % to about 95 wt %, about 80 wt % toabout 90 wt %, about 85 wt % to about 95 wt %, or about 90 wt % to about95 wt %, based on the combined weight of the polyethylene and the one ormore other polymers.

The polyethylene and/or a polymer blend containing the polyethylene canbe used for a wide variety of applications. For example, thepolyethylene and/or a polymer blend that includes the polyethylene canbe particularly useful in extrusion coating, cast film processes, blownfilm processes, thermoforming processes, injection molding processes,and lamination processes. Exemplary end uses can include, but are notlimited to, coatings, films, film-based products, diaper backsheets,housewrap, wire and cable coatings, articles formed by moldingtechniques, e.g., injection or blow molding, foaming, casting, andcombinations thereof. End uses can also include products made fromfilms, e.g., bags, packaging, and personal care films, pouches, medicalproducts, such as for example, medical films and intravenous (IV) bags.In end uses that include films, either or both of the surfaces of thefilms produced from the polymer blend can be modified by known andconventional post-forming techniques such as corona discharge, chemicaltreatment, flame treatment, and the like.

In one example, monolayer films can be prepared from the polyethyleneand/or a polymer blend containing the polyethylene. In another example,multilayer films can be prepared from the polyethylene and/or blendsthereof. Multilayer films can include one or more layers of film madefrom polymers other than the polyethylene and/or blends thereof.

To facilitate discussion of different multilayer film structures, thefollowing notation is used herein. Each layer of a film is denoted “A”or “B”, where “A” indicates a film layer not containing the polyethyleneand “B” indicates a film layer having the polyethylene. Where a filmincludes more than one A layer or more than one B layer, one or moreprime symbols (′, ″, ′″, etc.) are appended to the A or B symbol toindicate layers of the same type that can be the same or can differ inone or more properties, such as chemical composition, density, meltindex, thickness, etc. Finally, the symbols for adjacent layers areseparated by a slash (/). Using this notation, a three-layer film havingan inner or core layer of the polyethylene disposed between two outer,conventional film layers, i.e. not containing the polyethylene, would bedenoted A/B/A′. Similarly, a five-layer film of alternatingconventional/polymer blend layers would be denoted A/B/A′/B′/A″. Unlessotherwise indicated, the left-to-right or right-to-left order of layersdoes not matter, nor does the order of prime symbols. For example, anA/B film is equivalent to a B/A film, and an A/A′/B/A″ film isequivalent to an A/B/A′/A″ film, for purposes described herein.

The relative thickness of each film layer is similarly denoted, with thethickness of each layer relative to a total film thickness of 100(dimensionless) indicated numerically and separated by slashes; e.g.,the relative thickness of an A/B/A′ film having A and A′ layers of 10 μmeach and a B layer of 30 μm is denoted as 20/60/20. Exemplaryconventional films can be as discussed and described in, for example,U.S. Pat. Nos. 6,423,420; 6,255,426; 6,265,055; 6,093,480; 6,083,611;5,922,441; 5,907,943; 5,907,942; 5,902,684; 5,814,399; 5,752,362;5,749,202; 7,235,607; 7,601,409; RE 38,658; RE 38,429; U.S. PatentApplication Publication No. 2007/0260016; and WO Publication No.WO2005/065945.

For the various films described herein, the “A” layer can be formed ofany material known in the art for use in multilayer films or infilm-coated products. Thus, for example, the A layer can be formed of asecond polyethylene (homopolymer or copolymer), i.e., a polyethylenethat differs in at least one property from the polyethylenes discussedand described herein, and the second polyethylene can be, for example, aVLDPE, LDPE, LLDPE, MDPE, HDPE, as well as other polyethylenes known inthe art. In another example, the A layer can be formed of a polyethylene(homopolymer or copolymer), a non-polyethylene polymer, e.g. apolypropylene, or a blend of a polyethylene and a non-polyethylenepolymer.

Illustrative additional polymers (non-polyethylenes) that can be used asor in the A layer can include, but are not limited to, otherpolyolefins, polyamides, polyesters, polycarbonates, polysulfones,polyacetals, polylactones, acrylonitrile-butadiene-styrene resins,polyphenylene oxide, polyphenylene sulfide, styrene-acrylonitrileresins, styrene maleic anhydride, polyimides, aromatic polyketones, ormixtures of two or more of the above. Suitable polyolefins can include,but are not limited to, polymers comprising one or more linear, branchedor cyclic C₂ to C₄₀ olefins, preferably polymers comprising propylenecopolymerized with one or more C₃ to C₄₀ olefins, preferably a C₃ to C₂₀alpha olefin, more preferably C₃ to C₁₀ alpha-olefins.

In multilayer structures, one or more A layers can also be anadhesion-promoting tie layer, such as PRIMACOR™ ethylene-acrylic acidcopolymers available from Dow Chemical Co. and/or ethylene-vinyl acetatecopolymers. Other materials for A layers can be, for example, foil,nylon, ethylene-vinyl alcohol copolymers, polyvinylidene chloride,polyethylene terephthalate, oriented polypropylene, ethylene-vinylacetate copolymers, ethylene-acrylic acid copolymers,ethylene-methacrylic acid copolymers, graft modified polymers, andpaper.

One or more A layers can be replaced with a substrate layer, such asglass, plastic, paper, metal, etc., or the entire film can be coated orlaminated onto a substrate. Thus, although the discussion herein focuseson multilayer films, the films that include the polyethylene can also beused as coatings; e.g., films (monolayer and multilayer) can be coatedonto a substrate such as paper, metal, glass, plastic and othermaterials capable of accepting a coating.

The polymer film can be a multilayer film with any of the followingexemplary structures: (a) two-layer films, such as A/B and B/B′; (b)three-layer films, such as A/B/A′, A/A′/B, B/A/B′ and B/B′/B″; (c)four-layer films, such as A/A′/A″/B, A/A′/B/A″, A/A′/B/W, A/B/A′/B′,A/B/B′/A′, B/A/A′/B′, A/B/B′/B″, B/A/B′/B″ and B/B′/B″/B′″; (d)five-layer films, such as A/A′/A″/A′″/B, A/A′/A″/B/A′″, A/A′/B/A″/A′″,A/A′/A″/B/B′, A/A′/B/A″/B′, A/A′/B/B′/A″, A/B/A′/B′/A″, A/B/A′/A″/B,B/A/A′/A″/B′, A/A′/B/B′/B″, A/B/A′/B′/B″, A/B/B′/B″/N, B/A/A′/B′/B″,B/A/B′/A′/B″, B/A/B′/B″/N, A/B/B′/B″/B′″, B/A/B′/B″/B′″, B/B′/A/B″/B′″,and B/B′/B″/B′″/B″″; and similar structures for films having six, seven,eight, nine, twenty-four, forty-eight, sixty-four, one hundred, or anyother number of layers. It should be appreciated that films having stillmore layers can be formed using polymer blends, and such films arewithin the scope of the invention.

The polyethylene and/or a blend thereof can be formed into monolayerand/or multilayer films by any means known including any blown filmprocess known in the art, including bubble and double-bubble processes,cast processes, e.g., cast film and extrusion coating, injectionmolding, blow-molding, sheet extrusion, and the like. For example, thepolyethylene can be extruded in a molten state through a flat die andthen cooled to form a film. In another example, the polyethylene can beused as a sealant which can be extrusion coated onto a substrate eitherin the form of a monolayer or a coextruded extrudate.

In one example, in a typical extrusion coating process, the polyethyleneand/or the polyethylene and one or more other polymers, e.g., thepolyethylene and a linear polyethylene, can be fed to an extruder wherethe polyethylene or the polyethylene and one or more other polymersis/are melted, mixed, and extruded through the slit die at a temperaturetypically in the range of about 275° C. to about 340° C. A mixing screwwith barrier elements can be utilized. The extrudate can contact a chillroll which may be high gloss, matt, or embossed. A typical chill rolltemperature can range from about 25° C. to 35° C. As is known in theart, a multi-layer co-extrusion can be performed with two or more layerswith at least one of the layers including the polyethylene or a polymerblend including the polyethylene. The die width, die gap, extrusionrate, and substrate are chosen to provide the desired extrudate width,thickness, and production rate. Both the substrate and the coatedsurface can be surface treated with such techniques as are known in theart such as corona or plasma treatment. The extruded surface may befurther treated with techniques such as embossing, silane treatment forthe preparation of release papers, and other techniques and methods asare known in the art.

In another example, cast films can be prepared using a cast film linemachine as follows. Pellets of the polyethylene, alone or mixed with oneor more other polymers, can be melted at a temperature typically rangingfrom about 275° C. to about 325° C. for cast polymers (depending uponthe particular polymer(s) used), with the specific melt temperaturebeing chosen to match the melt viscosity of the particular polymer(s).In the case of a multilayer cast film, the two or more different meltscan be conveyed to a coextrusion adapter that combines the two or moremelt flows into a multilayer, coextruded structure. This layered flowcan be distributed through a single manifold film extrusion die to thedesired width. The die gap opening is typically about 600 μm (0.025inches). The material can then be drawn down to the final gauge. Thematerial draw down ratio is typically about 21:1 for 20 μm (0.8 mils)films. A vacuum box, edge pinners, air knife, or any combinationthereof, can be used to pin the melt exiting the die opening to aprimary chill roll maintained at about 32° C. (80° F.). The resultingfilm can be collected on a winder. The film thickness can be monitoredby a gauge monitor, and the film can be edge trimmed by a trimmer. Atypical cast line rate is from about 76.2 m to about 610 m (250 ft toabout 2,000 feet) per minute. One skilled in the art will appreciatethat higher rates may be used for similar processes such as extrusioncoating. One or more optional treaters can be used to surface treat thefilm, if desired. Such chill roll casting processes and apparatus can beas discussed and described in, for example, The Wiley-Encyclopedia ofPackaging Technology, Second Edition, A. L. Brody and K. S. Marsh, Ed.,John Wiley and Sons, Inc., New York (1997). Although chill roll castingis one example, other forms of casting may be employed, such asextrusion coating.

The total thickness of the resulting monolayer and/or multilayer filmscan vary based, at least in part, on the particular end use application.A total film thickness of about 5 μm to about 100 μm, more typicallyabout 10 μm to about 50 μm, can be suitable for most applications. Thoseskilled in the art will appreciate that the thickness of individuallayers for multilayer films can be adjusted based on desired end useperformance, end use product, equipment capability, and other factors.

Films made from the polyethylene or a polymer blend of the polyethyleneand one or more other polymers as discussed and described herein and/orthe process of making the films can have improved properties. Forexample, films that include the polyethylene can be produced withreduced motor load and/or increased draw-down rates during extrusion ofthe film as compared to traditional polymer blends. The reduction inmotor load depends on the particular equipment used for extrusion. Ithas been surprisingly and unexpectedly discovered that the polyethyleneand/or a polymer blend of the polyethylene and LDPE discussed anddescribed herein can substantially reduce the motor load required toextrude the polyethylene and/or the polymer blend by about 10% or more,about 12% or more, about 14% or more, about 16% or more, about 18% ormore, about 20% or more, about 22% or more, about 24% or more, about 26%or more, about 28% or more, or about 30% or more or more as compared toa comparative polyethylene and/or a comparative polymer blend containingthe same LDPE and a traditional polyethylene when both the polyethyleneand the comparative polyethylene have a melt index (I₂) of about 1 g/10min and the LDPE has a melt index (I₂) of about 1.9 g/10 min.

A variety of additives can be employed in the polyethylene compositionsand/or polymer blends containing the polyethylene discussed anddescribed herein depending upon the performance characteristics requiredby a particular application. The additives can be included in thepolyethylene and/or in a product formed from the polyethylene, such asan extruded film, as desired. In one example, the polyethylene discussedand described herein can include from about 0.1 wt % to about 40 wt %additives, based on the total weight of the polyethylene. In anotherexample, the polyethylene can include from about 5 wt % to about 25 wt %additives, based on the total weight of the polyethylene.

Examples of such additives include, but are not limited to, tackifiers,waxes, functionalized polymers such as acid modified polyolefins and/oranhydride modified polyolefins, antioxidants (e.g., hindered phenolicssuch as IRGANOX® 1010 or IRGANOX® 1076 available from Ciba-Geigy),(e.g., IRGAFOS® 168 available from Ciba-Geigy), oils, compatabilizers,fillers, adjuvants, adhesion promoters, plasticizers, low molecularweight polymers, blocking agents, antiblocking agents, anti-staticagents, release agents, anti-cling additives, colorants, dyes, pigments,processing aids, UV stabilizers, heat stabilizers, neutralizers,lubricants, surfactants, nucleating agents, flexibilizers, rubbers,optical brighteners, colorants, diluents, viscosity modifiers, oxidizedpolyolefins, and any combination thereof. Additives can be combined withone or both of the first or linear polyethylene and/or may be combinedwith the blend of the first and linear polyethylene as furtherindividual components, in masterbatches, or in any combination thereof.

Examples

To provide a better understanding of the foregoing discussion, thefollowing non-limiting examples are provided. All parts, proportions andpercentages are by weight unless otherwise indicated.

Electron donor-free Ziegler Natta catalysts were used to produce thepolymers of Examples 1-19. Ziegler-Natta type catalysts were used toproduce the comparative examples C1-C17. The electron donor-freeZiegler-Natta catalyst used to produce the polymers of Examples 1-9 wasprepared according to the following procedure. About 613 g of Davison955 silica purchased from W. R. Grace & Co. that had been previouslycalcined at 600° C. was charged to a 6 liter mix tank under an inertnitrogen atmosphere. About 2.3 kg of dry, degassed hexane was added tothe mix tank and the slurry was heated to a temperature of about 60° C.with mixing. About 865 g of a 1.2 M n-butylethylmagnesium (BEM) solutionin heptane (19.6 wt % BEM) was added to the silica/hexane slurry overthe course of about 1 hour and was mixed for an additional hour at 60°C. to produce a first reacted product. About 198 g ofdimethyldichlorosilane (DMDCS) was added to the first reacted productover the course of about 1 hour and was mixed for an additional hour at60° C. to produce a second reacted product. About 290 g of titanium (IV)chloride was diluted with about 100 g of hexane before being added tothe second reacted product over the course of about 1 hour and was heldat a temperature of about 60° C. and further mixed for about 1 hour andthen the volatiles were removed therefrom under reduced pressure toproduce the electron donor-free Ziegler-Natta catalyst capable ofintroducing Long Chain Branching (LCB) in the polymer. The LCB-capableelectron donor-free Ziegler-Natta catalyst was in the form of afree-flowing powder. A second batch of the same catalyst used to producethe polymers of Examples 1-9 was prepared and was used to produce thepolymers of Examples 16-19. The second batch of catalyst was preparedaccording to the same procedure as the first batch. Both catalysts wereanalyzed for Ti, Mg, Cl⁻ and hexane content, the results of which areshown in Table 1 below.

TABLE 1 Resid- ual Cl⁻ Mg Ti Hexane Catalyst (mmol/g) (mmol/g) (mmol/g)Mg/Ti (wt %) Used to 4.82 1.58 0.86 1.84 0.04 Produce the Polymers ofExamples 1-9 Used to 4.24 1.72 0.70 2.46 <0.01 Produce the Polymers ofExamples 16-19

The electron donor-free Ziegler-Natta catalyst used to prepare thepolymers of Examples 10, 11, and 13-15 was prepared according to thefollowing procedure. About 415 g of Davison 955 silica purchased from W.R. Grace & Co. that had been previously calcined at 600° C. was added toa 6 liter mix tank under an inert nitrogen atmosphere. About 1.4 kg ofdry, degassed hexane was added to the mix tank and the slurry was heatedto a temperature of about 30° C. with mixing. About 524 g of a 1.3 Mn-butylethylmagnesium (BEM) solution in heptane (19.9 wt % BEM) wasadded to the silica/hexane slurry over the course of about 30 minutesand was mixed for an additional 19 hours at 30° C. to produce a firstreacted product. About 1,210 g of a 1.0 M ethylaluminum dichloride(EADC) solution in hexane (17.4 wt %) was added over a 30 minute periodto the first reacted product and was mixed for an additional 4 hours at30° C. to produce a second reacted product. About 21.6 g oftetraisopropyltitanate (TIPT) was added to the second reacted productand mixed for an additional 16 hours at 30° C. and then the volatileswere removed under reduced pressure to form the electron donor-freeZiegler-Natta catalyst. The electron donor-free Ziegler-Natta catalystwas a free-flowing powder.

The electron donor-free Ziegler-Natta catalyst used to prepare thepolymer of Example 12 was prepared according to the following procedure.About 465 g of Davison 955 silica purchased from W. R. Grace & Co. thathad been previously calcined at about 600° C. was added to a 6 liter mixtank under an inert atmosphere of nitrogen. About 1.5 kg of dry,degassed hexane was added to the mix tank and the slurry was heated to atemperature of about 30° C. with mixing. About 1,200 g of a 1.2 Mn-butylethylmagnesium (BEM) solution in heptane (19.6 wt % BEM) wasadded to the silica/hexane slurry over the course of about 30 minuteswith mixing to produce a first mixture. The first mixture was mixed foran additional 19 hours at 30° C., after which the solids were filteredoff. The solids were then suspended in about 1.6 liters of hexane andmixed for about five minutes and then filtered off. This wash/filtercycle was repeated two additional times for a total of three wash/filtercycles. About 1.4 liters of hexane was added to the solids and theslurry was heated to about 30° C. with mixing. About 1,630 g of a 1.0 Methylaluminum dichloride (EADC) solution in hexane (17.4 wt %) was addedover a 30 minute period to produce a second mixture. The second mixturewas mixed for an additional 4 hours at a temperature of about 30° C.About 24.2 g of tetraisopropyltitanate (TIPT) was added to the secondmixture to produce the electron donor-free Ziegler-Natta catalyst orcatalyst composition. The electron donor-free Ziegler-Natta catalystcomposition was mixed for an additional 16 hours at 30° C., after whichthe solids were filtered off. The solids were then suspended in about1.6 liters of hexane and mixed for about five minutes before beingfiltered off. This wash/filter cycle was repeated two additional timesfor a total of three wash/filter cycles. Next, the volatiles of theelectron donor-free Ziegler-Natta catalyst composition were removedunder reduced pressure. A catalyst in the form of a free-flowing powderwas recovered.

It should be noted that the electron donor-free Ziegler-Natta catalystsused to produce the polymers of Examples 1-19 were prepared without theaddition of any electron donors as discussed and described above. Assuch, the Ziegler-Natta catalyst can be referred to as a “donor freecatalyst.” The electron donor-free Ziegler-Natta catalysts used toprepare the polymers of Examples 10-15 were analyzed for Ti, Mg, Al, andcontent, the results of which are shown in Table 2 below.

TABLE 2 Cl⁻ Mg Ti Al Catalyst (mmol/g) (mmol/g) (mmol/g) (mmol/g) Mg/TiUsed to 4.41 1.20 0.12 2.22 10.30 Produce the Polymers of Examples 10,11, and 13-15 Used to 4.45 1.91 0.12 0.95 15.90 Produce the Polymer ofExample 12

A gas phase fluidized bed polymerization reactor of the UNIPOL™ PEProcess design having a nominal diameter of about 35.6 cm (about 14inches) was used for the continuous production of both linear lowdensity polyethylene (LLDPE) and high density polyethylene (HDPE). Inthese cases, the cycle gas blower was situated upstream of the cycle gasheat exchanger in the gas recirculation loop but the two could have beenreversed to reduce the gas temperature where it entered the heatexchanger. The cycle pipe was about 5.1 cm (about 2 inches) in diameterand its flow rate was manipulated by a ball valve in the cycle line tocontrol the superficial gas velocity in the fluid bed at the desiredrate. Monomers and gaseous components were added upstream of the coolerbefore the blower, at the blower impeller or after the blower. Theelectron donor-free Ziegler-Natta catalyst system was continuously addedin discrete small aliquots via an about 0.317 cm (about 0.125 inch) tubedirectly to the fluidized bed at a height about 0.1 m to 2 m above thedistributor plate and most preferably at about the 0.2 m to about 1.2 mrange using a nitrogen carrier gas flow at a location about 15% to about50% of the reactor diameter. Triethylaluminum (TEAl) was utilized as aco-catalyst and added to the reactor as a solution in hexane. Where acontinuity additive was used, a 50/50 mixture of a hydroxyethyl stearylamine and aluminum distearate continuity additive slurry was metered tothe reactor from an agitated slurry feeding vessel to maintain thedesired concentration in the bed based on polymer production rate usingan inert hydrocarbon, such as isopentane, as a carrier medium. Polymerproduct was withdrawn periodically from the reactor through a dischargeisolation tank in aliquots of about 0.2 kg to 5 kg to maintain a desiredapproximate average fluidized bed level or weight.

The polymerization conditions and results for the production of thepolymers of Examples 1-19 is shown in Tables 3A-C below. For H₂/C₂ massfeed ratio in the tables below the term mlb/lb refers to millipounds ofhydrogen per pound of ethylene.

TABLE 3A Examples Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Polymer TypeHDPE HDPE HDPE HDPE HDPE HDPE HDPE Catalyst Ti Content (wt %) 4.11 4.114.11 4.11 4.11 4.11 4.11 Catalyst Al Content (wt %) 0.11 0.11 0.11 0.110.11 0.11 0.11 Catalyst Mg Content (wt %) 3.84 3.84 3.84 3.84 3.84 3.843.84 Prod Rate (lbs/hr) 34.1 38 33.8 37 38.2 39.5 36 Residence Time(hrs) 3.2 2.9 3.3 3 3 2.8 3 C₂ Partial Pressure (psia) 120 120 101 120120 120 120 H₂/C₂ (m/m) 0.135 0.180 0.182 0.182 0.282 0.218 0.169 C₄/C₂Conc. Ratio (m/m) 0.0113 0.0178 0.0126 0.0171 0.0089 0.0205 0.0224 C₆/C₂Conc. Ratio (m/m) — — — — — — — H₂/C₂ Mass Feed Ratio (mlb/lb) 1.21 1.861.94 1.86 3.07 2.09 1.78 C₄/C₂ Mass Feed Ratio (lb/lb) 0.0068 0.00960.0096 0.0095 0.0066 0.0108 0.0110 C₆/C₂ Mass Feed Ratio (lb/lb) — — — —— — — Isopentane (mole %) 0.19 0.17 0.3 0.16 0.28 0.3 0.3 RX Pressure(psig) 346 346 346 346 346 346 346 RX Temperature (° C.) 102 102 102 102102 102 102 Gas Velocity (ft/sec) 1.9 1.91 1.66 1.93 1.97 1.96 1.96 BedWeight (lbs) 110 110 111 110 115 110 110 Fluid Bulk Density (lb/ft³)13.9 13.3 12.6 13.2 15 12.5 12.2 Co-catalyst ID TEAl TEAl TEAl TEAl TEAlTEAl TEAl Co-catalyst Conc. (wt %) 1.0 1.0 1.0 1.0 1.0 1.0 1.0Co-catalyst Feed, (cc/hr) 75.1 75 135.3 74.8 151.5 150.5 150.3 ReactorCo-catalyst Conc. - 30 27 55 28 54 52 57 Prod. Rate Basis (ppmw) Cont.Additive None None None None None None None Continuity Additive Conc.(wt %) — — — — — — — Continuity Additive Feed (cc/hr) — — — — — — —Reactor Cont. Additive — — — — — — — Conc. - Prod Rate Basis (ppmw) Cat.Prod. - Ti ICPES 9,536 10,883 — — — — — Basis (g PE/g Catalyst) MaterialBalance Cat. 13,008 15,077 13,967 14,680 10,464 14,070 15,220 Prod, (gPE/g Catalyst) I₂ Melt Index (dg/min) 0.40 1.01 1.02 1.03 3.24 2.12 1.13MFR, I₂₁/I₂ 40.0 37.8 36.4 38.8 33.8 33.8 35.4 Polymer Density (g/cc)0.9548 0.9549 0.9555 0.9544 0.9597 0.9562 0.9532

TABLE 3B Examples Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Polymer TypeHDPE HDPE HDPE HDPE HDPE HDPE Catalyst Ti Content (wt %) 4.11 4.11 0.590.59 0.56 0.59 Catalyst Al Content (wt %) 0.11 0.11 2.57 2.57 5.99 2.57Catalyst Mg Content (wt %) 3.84 3.84 4.65 4.65 2.92 4.65 Prod Rate(lbs/hr) 36.4 33.5 33.7 29.8 23.9 32.2 Residence Time (hrs) 3 3.3 3.43.9 4.8 3.6 C₂ Partial Pressure (psia) 120 120 120 120 120 120 H₂/C₂(m/m) 0.155 0.162 0.245 0.153 0.258 0.16 C₄/C₂ Conc. Ratio (m/m) 0.01820.0141 0.0096 0.0094 0.0082 0.0090 C₆/C₂ Conc. Ratio (m/m) — — — — — —H₂/C₂ Mass Feed Ratio (mlb/lb) 1.61 1.90 2.72 1.66 3.48 1.85 C₄/C₂ MassFeed Ratio (lb/lb) 0.0097 0.0086 0.0095 0.0074 0.0082 0.0076 C₆/C₂ MassFeed Ratio (lb/lb) — — — — — — Isopentane (mole %) 0.31 0.3 0.16 0.180.75 0.17 RX Pressure (psig) 346 346 347 347 347 347 RX Temperature (°C.) 102 102 102 102 102 102 Gas Velocity (ft/sec) 1.95 1.95 1.8 1.8 1.81.81 Bed Weight (lbs) 109 109 115 115 115 115 Fluid Bulk Density(lb/ft³) 12.3 12.6 17.9 17.8 16.8 17.7 Co-catalyst ID TEAl TEAl TEAlTEAl TEAl TEAl Co-catalyst Conc. (wt %) 1.0 1.0 1.0 1.0 1.0 1.0Co-catalyst Feed (cc/hr) 149.9 149.9 74.8 74.9 373.9 74.8 ReactorCo-catalyst Conc. - 56 61 30 34 214 32 Prod. Rate Basis (ppmw) Cont.Additive None None None None None None Continuity Additive Conc. (wt %)— — — — — — Continuity Additive Feed (cc/hr) — — — — — — Reactor Cont.Additive — — — — — — Conc. - Prod Rate Basis (ppmw) Cat. Prod. - TiICPES — 9,222 — — 1,422 3,758 Basis (g PE/g Catalyst) Material BalanceCat. 14,460 12,184 4,629 3,801 1,705 4,106 Prod, (g PE/g Catalyst) I₂Melt Index (dg/min) 0.86 0.84 0.40 0.43 0.94 0.960 MFR, I₂₁/I₂ 37.7 37.333.0 32.8 30.6 30.5 Polymer Density (g/cc) 0.9544 0.9553 0.9531 0.95410.9531 0.9541

TABLE 3C Examples Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 Ex. 19 Polymer TypeHDPE HDPE HDPE HDPE LLDPE LLDPE Catalyst Ti Content (wt %) 0.59 0.593.34 3.34 3.34 3.34 Catalyst Al Content (wt %) 2.57 2.57 0.167 0.1670.167 0.167 Catalyst Mg Content (wt %) 4.65 4.65 4.18 4.18 4.18 4.18Prod Rate (lbs/hr) 31.3 33 35.1 30.4 36.1 32.1 Residence Time (hrs) 3.63.4 2.81 3.05 2.89 2.9 C₂ Partial Pressure (psia) 120 120 120.2 120.1 8080 H₂/C₂ (m/m) 0.119 0.121 0.1583 0.1796 0.1248 0.1102 C₄/C₂ Conc. Ratio(m/m) 0.0052 0.0048 0.0178 0.0175 — 0.376 C₆/C₂ Conc. Ratio (m/m) — — —— 0.139 — H₂/C₂ Mass Feed Ratio (mlb/lb) 1.09 1.13 3.52 3.65 1.92 1.79C₄/C₂ Mass Feed Ratio (lb/lb) 0.0052 0.0050 0.0135 0.0128 — 0.191 C₆/C₂Mass Feed Ratio (lb/lb) — — — — 0.160 — Isopentane (mole %) 0.18 0.180.19 0.23 1.74 1.28 RX Pressure (psig) 347 347 346.4 346.6 346.6 346 RXTemperature (° C.) 102 102 102 102 88 88 Gas Velocity (ft/sec) 1.82 1.851.81 1.73 1.93 1.8 Bed Weight (lbs) 114 113 99 93 104 93 Fluid BulkDensity (lb/ft³) 17.5 18.2 10.3 11.7 13.4 10.8 Co-catalyst ID TEAl TEAlTEAl TEAl TEAl TEAl Co-catalyst Conc. (wt %) 1.0 1.0 1.0 1.0 1.0 1.0Co-catalyst Feed (cc/hr) 75.3 39.9 135.6 135.6 129.2 135.5 ReactorCo-catalyst Conc. - 33 17 53 61 49 58 Prod. Rate Basis (ppmw) Cont.Additive None None None None Yes Yes Continuity Additive Conc. (wt %) —— — — 15 15 Continuity Additive Feed (cc/hr) — — — — 1.5 0.5 ReactorCont. Additive — — — — 15.6 5.8 Conc. - Prod Rate Basis (ppmw) Cat.Prod. - Ti ICPES 4,014 4,538 — 10,050 9,386 8,743 Basis (g PE/gCatalyst) Material Balance Cat. 3,992 4,205 13,181 14,495 10,300 11,438Prod, (g PE/g Catalyst) I₂ Melt Index (dg/min) 1.00 2.48 0.72 0.94 0.991.00 MFR, I₂₁/I₂ 31.0 32.8 40.7 37.5 42.0 37.3 Polymer Density (g/cc)0.9550 0.9576 0.9525 0.9538 0.9216 0.9180

The UCAT® A2020 (available from Univation Technologies LLC) was used toproduce the polymers of comparative examples C1 and C2. The SYLOPOL®5006 catalyst, acquired from Grace Davison, was used to produce thepolymers of comparative examples C3-C11. The polymerization results forcomparative examples C1-C11 are shown in Tables 4A-B below.

TABLE 4A Examples C1 C2 C3 C4 C5 C6 Polymer Type HDPE HDPE HDPE HDPEHDPE HDPE Catalyst Ti Content (wt %) 1.06 1.06 1.31 1.31 1.31 1.31Catalyst Al Content (wt %) 2.93 2.93 5.10 5.10 5.10 5.10 Catalyst MgContent (wt %) 1.66 1.66 3.17 3.17 3.17 3.17 Prod Rate (lbs/hr) 34.238.7 38.3 35.2 33.3 38.7 Residence Time (hrs) 3.2 2.9 3.0 3.3 3.5 3.0 C₂Partial Pressure (psia) 100 120 120 120 120 120 H₂/C₂ (m/m) 0.418 0.1800.257 0.268 0.360 0.346 C₄/C₂ Conc. Ratio (m/m) 0.0109 0.0078 0.00620.0056 0.0078 0.0102 C₆/C₂ Conc. Ratio (m/m) — — — — — — H₂/C₂ Mass FeedRatio (mlb/lb) 1.780 1.85 3.03 3.17 5.17 4.60 C₄/C₂ Mass Feed Ratio(lb/lb) 0.0078 0.0053 0.0051 0.0051 0.0062 0.0073 C₆/C₂ Mass Feed Ratio(lb/lb) — — — — — — Isopentane (mole %) 3.55 4.11 0.38 0.29 0.28 0.29 RXPressure (psig) 347 347 347 347 347 347 RX Temperature (° C.) 102 102102 102 102 102 Gas Velocity (ft/sec) 2.00 1.98 2.00 1.99 1.97 1.97 BedWeight (lbs) 111 112 115 115 116 115 Fluid Bulk Density (lb/ft³) 15.215.3 17.6 17.5 17.6 17.4 Co-catalyst ID TEAl TEAl TEAl TEAl TEAl TEAlCo-catalyst Conc. (wt %) 2.5 2.5 1.0 1.0 1.0 1.0 Co-catalyst Feed(cc/hr) 299.0 300.1 150.6 149.6 150.5 150.3 Reactor Co-catalyst Conc. -299 265 54 58 62 53 Prod Rate Basis (ppmw) Cont. Additive None None NoneNone None None Continuity Additive Conc. (wt %) — — — — — — ContinuityAdditive Feed (cc/hr) — — — — — — Reactor Cont. Additive — — — — — —Conc. - Prod Rate Basis (ppmw) Cat. Prod. - Ti ICPES — 3,464 — 5,928 — —Basis (g PE/g Catalyst) Material Balance Cat. 6,734 5,518 13,421 11,86110,809 12,538 Prod, (g PE/g Catalyst) I₂ Melt Index (dg/min) 0.94 1.030.41 0.43 1.05 1.04 MFR, I₂₁/I₂ 24.4 23.6 35.0 35.8 32.5 33.4 PolymerDensity (g/cc) 0.9529 0.9545 0.9532 0.9537 0.9544 0.9538

TABLE 4B Examples C7 C8 C9 C10 C11 Polymer Type HDPE HDPE HDPE HDPE HDPECatalyst Ti Content (wt %) 1.31 1.31 1.31 1.31 1.31 Catalyst Al Content(wt %) 5.10 5.10 5.10 5.10 5.10 Catalyst Mg Content (wt %) 3.17 3.173.17 3.17 3.17 Prod Rate (lbs/hr) 37.3 36.7 39.1 42.8 17.9 ResidenceTime (hrs) 3.1 3.2 3.0 2.7 6.4 C₂ Partial Pressure (psia) 120 120 120120 100 H₂/C₂ (m/m) 0.340 0.334 0.338 0.404 0.344 C₄/C₂ Conc. Ratio(m/m) 0.0096 0.0092 0.0096 0.0015 0.0164 C₆/C₂ Conc. Ratio (m/m) — — — —— H₂/C₂ Mass Feed Ratio (mlb/lb) 4.85 4.66 4.62 5.65 5.23 C₄/C₂ MassFeed Ratio (lb/lb) 0.0071 0.0070 0.0071 0.0024 0.0163 C₆/C₂ Mass FeedRatio (lb/lb) — — — — — Isopentane (mole %) 0.14 0.28 0.53 0.26 0.33 RXPressure (psig) 347 347 347 347 347 RX Temperature (° C.) 102 102 102102 100 Gas Velocity (ft/sec) 1.97 1.97 1.97 1.97 1.97 Bed Weight (lbs)116 116 117 118 115 Fluid Bulk Density (lb/ft³) 16.2 17.3 17.8 18.2 17.3Co-catalyst ID TEAl TEAl TEAl TEAl TEAl Co-catalyst Conc. (wt %) 1.0 1.01.0 1.0 1.0 Co-catalyst Feed (cc/hr) 74.8 149.7 300.4 149.5 150.0Reactor Co-catalyst Conc. - 27 56 105 48 114 Prod Rate Basis (ppmw)Cont. Additive None None None None None Continuity Additive Conc. (wt %)— — — — — Continuity Additive Feed (cc/hr) — — — — — Reactor Cont.Additive — — — — — Conc. - Prod Rate Basis (ppmw) Cat. Prod. - Ti ICPES8,037 6,121 4,651 — — Basis (g PE/g Catalyst) Material Balance Cat.14,653 11,890 8,715 9,699 10,182 Prod, (g PE/g Catalyst) I₂ Melt Index(dg/min) 0.91 0.78 1.03 1.03 1.04 MFR, I₂₁/I₂ 33.4 34.4 32.3 37.8 31.9Polymer Density (g/cc) 0.9531 0.9535 0.9539 0.9590 0.9507

The polymer of comparative example C12 was TUFLIN® HS-7098 NT 7 (acopolymer of ethylene and hexene) and was acquired from The Dow ChemicalCompany. The polymer of comparative example C13 was DFDA 7047 NT 7 (acopolymer of ethylene and butene) and was acquired from The Dow ChemicalCompany. The polymer of comparative example C14 was produced with LDPE501i polyethylene and was acquired from The Dow Chemical Company. Thepolymer of comparative example C16 was AFFINITY™ PL 1880G (a copolymerof ethylene and octene) and was acquired from The Dow Chemical Company.The polymer of comparative example C17 was EXCEED® 1018CA (a copolymerof ethylene and hexene) and was acquired from ExxonMobil Chemical.

Comparative example C15 was produced using a 2-liter autoclave gas phasereactor. The following procedure was used to produce the polymer ofcomparative example C15. The sealed reactor was cycled several timesthrough a heat and nitrogen purge step to ensure that the reactor wasclean and under an inert nitrogen atmosphere. About 1 L of liquidisobutane was added to the sealed reactor at ambient temperature. Acharge of about 1.3 ml of 1M triethyl aluminum was added to the reactorfrom a shot cylinder using nitrogen pressure. The reactor agitator wasturned on and set to 800 rpm. Hydrogen (3.83 L) and 20 ml of 1-hexenewere added to the reactor. The reactor was heated to a temperature ofabout 85° C. and ethylene was added to achieve a 125 psi partialpressure. A nominal 35 mg charge of UCAT® A2020 (available fromUnivation Technologies LLC) was added to the reactor from a shotcylinder using nitrogen pressure. The polymerization proceeded at about85° C. and ethylene was added continuously to maintain the reactor atconstant pressure. After one hour, the reactor was cooled to ambienttemperature, vented, opened, and the polymer product was recovered.

Selected properties for the polymers of Examples 1-19 and comparativeexamples C1-C17 are shown in Table 5 below.

TABLE 5 EVF Como- MI Density MFR MS Slope Ex. nomer (I₂) (g/cm₃) Mw MzMWD (I₂₁/I₂) (cN) (SSH) CHI Ex. 1 Butene 0.40 0.9548 143760 615200 5.9940.0 14.0 0.928 — Ex. 2 Butene 1.01 0.9549 121260 570400 6.26 37.8 8.5 —— Ex. 3 Butene 1.02 0.9555 120310 520500 5.84 36.4 7.3 — — Ex. 4 Butene1.03 0.9544 122190 575100 6.27 38.8 8.5 — — Ex. 5 Butene 3.24 0.959794390 404600 5.88 33.8 3.3 — — Ex. 6 Butene 2.12 0.9562 98230 3821005.50 33.8 4.8 — — Ex. 7 Butene 1.13 0.9532 109100 389300 4.97 35.4 6.7 —— Ex. 8 Butene 0.86 0.9544 118900 436600 5.48 37.7 8.3 — — Ex. 9 Butene0.84 0.9553 120400 439100 5.03 37.3 8.0 1.284 — Ex. 10 Butene 0.400.9531 165200 629200 6.08 33.0 6.8 0.452 — Ex. 11 Butene 0.43 0.9541162830 617600 6.14 32.8 6.5 — — Ex. 12 Butene 0.94 0.9531 135950 5247005.94 30.6 3.7 — — Ex. 13 Butene 0.96 0.9541 134060 551900 6.08 30.5 3.7— — Ex. 14 Butene 1.00 0.9550 134250 566700 6.27 31.0 3.8 0.631 — Ex. 15Butene 2.48 0.9576 113320 649900 6.83 32.8 2.2 — — Ex. 16 Butene 0.720.9525 132210 529500 5.58 40.7 8.2 1.030 0.459 Ex. 17 Butene 0.94 0.9538128910 581900 6.11 37.5 8.2 — 0.093 Ex. 18 Hexene 0.99 0.9216 119000483900 6.40 42.0 6.5 1.085 0.227 Ex. 19 Butene 1.00 0.9180 116055 4434005.55 37.3 5.8 1.174 0.391 C1 Butene 0.94 0.9529 120400 330700 3.95 24.43.3 — — C2 Butene 1.03 0.9545 118600 329400 4.26 23.6 2.9 — — C3 Butene0.41 0.9532 159300 631900 5.52 35.0 6.7 0.665 — C4 Butene 0.43 0.9537154100 636400 5.96 35.8 6.4 — — C5 Butene 1.05 0.9544 123300 465700 5.3332.5 3.7 — — C6 Butene 1.04 0.9538 127000 524700 5.62 33.4 3.6 — — C7Butene 0.91 0.9531 125800 446500 5.20 33.4 4.0 — — C8 Butene 0.78 0.9535133000 545600 5.71 34.4 4.5 — — C9 Butene 1.03 0.9539 123500 447000 5.3032.3 3.6 0.371 — C10 Butene 1.03 0.9590 118100 417800 5.50 37.8 4.0 — —C11 Butene 1.04 0.9507 124400 496200 5.65 31.9 3.6 — — C12 Hexene 1.000.9220 123300 387280 4.22 26.5 3.7 0.062 0.228 C13 Butene 1.00 0.9180125000 371660 3.97 24.5 3.7 0.086 0.395 C14 N/A 1.85 0.9202 76700 3044004.58 53.7 6.1 0.706 0.833 (LDPE) C15 None 0.41 0.9498 157140 510900 4.6923.0 7.2 0.157 — C16 Octene 0.98 0.9019 105141 189379 2.28 30.1 3.720.447 0.947 C17 Hexene 1.00 0.9180 84951 152680 2.13 15.9 2.54 0.0600.730

As shown in Table 5 above, the molecular weight distribution (MWD),slope of strain hardening (SSH), and melt flow ratio (MFR) for selectedexamples, namely, Examples 1, 9, 10, 14, 16, 18, and 19 and comparativeexamples C3, C9, and C12-C15, were measured. As shown, Examples 1, 9,16, 18, and 19 all had a MWD ranging from about 5.03 to about 6.4, a SSHgreater than 0.75, and a MFR greater than or equal to 8.33+(4.17×MWD).In contrast, not one of the comparative examples C3, C9, and C12-C15includes all three properties in combination with one another. Indeed,it is believed that polyethylenes having the unique combination of MWD,SSH, MFR, and heterogeneous short chain branching distributionassociated with Ziegler-Natta polymers are unique to the inventiveLCB-capable donor-free Ziegler-Natta catalyst polyethylenes.

Another property measured for selected examples, namely, Examples 16-19and comparative examples C12, C13, and C16 was the comonomerheterogeneity index (CHI). The CHI was determined according to followingprocedure. The data used and shown in Table 6 for the following CHImeasurement procedure was the data acquired for Ex. 19. For clarity andease of description some data is omitted from Table 6. However, the fullrange of experimental data for the data shown in Table 6 is shown in thegraph depicted in FIG. 1, which shows the Calculation of CHI from theCEF Data.

TABLE 6 Area Temp. Response Cumulative Calculated (° C.) Zeroed (S_(i))Cum_Norm × 10 Comonomer Ti Measured Hi Trapezoid Si nSi Ci 34.855 0 0 00 0 0.112792905 34.902 −0.001 0 0 0 0 0.112701549 34.948 0.001 0 0.0010.001 0 0.112612785 34.998 −0.001 0 0 0.001 0 0.112514719 35.048 −0.0020 0 0.001 0 0.1124192 n = 1 35.1 0 0 0 0.001 0 0.112317822 35.148 0 0 00.001 0 0.112224333 35.197 −0.001 0 0 0.001 0 0.1121294 35.244 −0.003 00 0.001 0 0.112038638 Data omitted for clarity 77.64 1.797 1.797 0.07327.468 3.075 0.036890771 77.681 1.801 1.801 0.093 27.561 3.0850.036824825 77.732 1.807 1.807 0.086 27.647 3.095 0.036741541 hT_(i)77.779 1.816 1.816 0.104 27.751 3.106 0.0366649 ahC_(i) 77.836 1.8211.821 0.076 27.827 3.115 0.036572069 Data omitted for clarity 85.2572.481 2.481 0.152 44.306 4.959 0.024718997 85.318 2.481 2.481 0.12444.431 4.973 0.024622744 85.368 2.48 2.48 0.095 44.525 4.984 0.024543881T_(m) 85.406 2.478 2.478 0.121 44.646 4.997 0.0244839 C_(m) 85.455 2.4782.478 0.127 44.773 5.011 0.024407127 85.506 2.48 2.48 0.119 44.892 5.0250.024326748 85.554 2.479 2.479 0.123 45.015 5.039 0.024251338 85.6042.476 2.476 0.119 45.134 5.052 0.024173364 Data omitted for clarity93.123 2.397 2.397 0.138 62.302 6.973 0.012529889 93.18 2.41 2.41 0.11962.421 6.987 0.012442021 93.229 2.425 2.425 0.109 62.53 6.9990.012366879 lT_(i) 93.274 2.441 2.441 0.089 62.619 7.009 0.0122987alC_(i) 93.311 2.455 2.455 0.107 62.726 7.021 0.012242985 93.354 2.472.47 0.146 62.872 7.037 0.012176941 93.413 2.487 2.487 0.129 63.0017.052 0.012087362 Data omitted for clarity 104.879 0.005 0.005 0 89.34110 0 104.915 0.005 0.005 0 89.341 10 0 104.95 0.004 0.004 0 89.341 10 0n = N 105.002 0.003 0.003 Calculated parameters C 0.5 (lC_(i)) 0.01224In this example, N = 1441 CHI 0.391 C 1.5 (lC_(i)) 0.03673 M50 34.973Total Wt 89.341

The Crystallization Elution Fractionation (CEF) data was tabulated froma temperature of 35° C. to 105° C. as Temperature (T) vs. ResponseHeight (H). Response data points less than 0 were set to zero forpurposes of the calculation. The data was collected at a frequency of atemperature interval of 0.5° C. or less (e.g., an interval of 0.2° C.).The cumulative curve was calculated according to the following steps:(1) S_(i)=(T_(i+1)−T_(i))×(H_(i)+H_(i+1))/2+Σ(S₁ . . . S_(i−i)), where His the response (mass=dWf/dT), (2) i=1 . . . N−1, (3) N=the total numberof points that range from the point closest to and greater than T=35.0°C. to the point closest to and less than T=105.0° C. inclusive, and (4)S_(i) was normalized according to: nS_(i)=10×S_(i)/S_(N). The mediantemperature T_(m) was the point where nS_(i) is closest to 5.0. Thecomonomer content at T_(m) was C_(m) and was calculated according to thefollowing steps: (1) C_(m)=1-exp(0.5533-(207.0/(273.12+T_(m)))), and (2)C_(i) was calculated for each measured T_(i):C_(i)=1-exp(0.5533-(207.0/(273.12+T_(i)))). The mass fraction (M₅₀)within the region 0.5×C_(i) to 1.5×C_(i) was calculated according to thefollowing steps: (1) lC_(i)=0.5×C_(i); (2) hC_(i)=1.5×C_(i); (3) Limitsof the range used was set by determining the C_(i) values calculatedclosest to lC_(i) and hC_(i): (a) alC_(i)=C_(i) closest to and greaterthan lC_(i); and (b) ahC_(i)=C_(i) closest to and less than hC_(i); (4)The T_(i) values equivalent to alC_(i) and ahC_(i) were identified: (a)lT_(i) ≡alC_(i), and (b) hT_(i) ≡ahC_(i); (5) The mass fraction in thisregion was calculated as in step 4 but within the range lT_(i) andhT_(i) inclusive (a) M50=Σ(T_(i+1)−T_(i))×(H_(i)+H_(i+1))/2 where irepresents the data points in the range lT_(i) to hT_(i−1) inclusiveCHI=M50/S_(N).

The CEF data comparing Ex. 18 to C12 and Ex. 19 to C13 are shown in thegraphs depicted in FIGS. 2 and 3, respectively.

Slope of Strain Hardening

The slope of strain hardening (SSH) as measured by extensional viscosityfixture was determined for Examples 1, 9, 10, 14, 16, 18, and 19 andcomparative examples C3, C9, and C12-C15, the values of which are shownin Table 5. The extensional viscosity fixture (EVF) analysis comparingExamples 18 and 19 to comparative examples C3, C12, and C13 is alsographically shown in FIG. 4. As shown in FIG. 4, Examples 18 and 19surprisingly and unexpectedly had a significant increase in theextensional viscosity at a strain hardening rate of 0.1 s⁻¹ and at atemperature of 150° C., measured according to the extensional viscosityfixture test discussed and described above.

Melt Strength

The melt strength for Example 1 was compared to comparative examples C3and C15 all having a melt index (I₂) of about 0.4 g/10 min. FIG. 5depicts the graphical representation of the melt strength for Ex. 1, C3,and C15. As shown in FIG. 5, the melt strength of the polyethylene ofEx. 1 surprisingly and unexpectedly far exceeds the melt strength ofcomparative examples C3 and C15.

Blown Film Experiments

Mono-layer films were formed from the polyethylenes of Examples 18 and19 and comparative examples C12 and C13 via a blown film process.Depending on the particular example, a LDPE resin (LDPE 501imanufactured by The Dow Chemical Company) was blended with the examplesin various amounts ranging from none or zero up to about 30 wt %, basedon the combined weight of the Ex. 18, 19, C12, or C13 polyethylene andthe LDPE 501i resin. The LDPE 501i resin had a melt index (I₂) of 1.9 MIand was acquired from Dow Chemical. The blown films had a nominalthickness of 25 μm or 12.5 μm. The commercially available comparativeresins (C12 and C13) were chosen because those resins have a very closematch with the inventive polyethylenes in terms of melt index anddensity. More particularly, the polyethylenes of Ex. 18 and comparativeexample C12 were both ethylene/hexene copolymers of melt index 1.0 anddensity 0.922 g/cm³; and the polyethylenes of Ex. 19 and comparativeexample C13 were both ethylene/butene copolymers that had a melt index1.0 and density 0.918 g/cm³. As such, Ex. 18 was compared to C12 and Ex.19 was compared to C13.

The blend components, i.e., the LDPE and the inventive polyethylene (Ex.18 or 19) or the LDPE and the comparative polyethylene (C13 or C14) wereweighed and tumble-blended in a rotating drum blender. The films wereblown on a Colin blown film apparatus capable of three layerco-extrusion that required operation of all three extruders. As such,even though a monolayer film was formed, all three extruders were usedand were fed with the same resin or resin blend.

The Colin blown film apparatus included three extruders, i.e., ExtruderA, B, and C. Extruders A and C each had a 25 mm barrel diameter and a25:1 L/D single flight forwarding screw. Extruder B had a 30 mm barreldiameter and a 25:1 L/D single flight forwarding screw. The combinedresin from the three extruders was fed to an annular die which had a diediameter of 60 mm, a die gap of 2 mm, and a maximum take-off speed ofabout 30 m/min. The blow up ratio (BUR) was about 2.5:1. The BUR isequal to the ratio of the Bubble Diameter to Die Diameter. The filmswere produced at the 25 μm or 12.5 μm thickness by adjusting thetake-off rate. Each extruder A, B, and C was operated at 50% of themaximum take-off rate to allow for variations in motor load and pressureto be accommodated without requiring a change in screw speed. Bubblestability was studied by measuring the minimum air flow rate at whichthe bubble would be stable for 5 seconds when blowing the 12.5 μm thickfilm samples. The experiments performed, extruder data, and bubble dataare shown in Table 7 below.

TABLE 7 Blown Film Experiment Extruder Data Melt Temp. Motor CurrentExtruder Resin Throughput Film Bubble LDPE (° C.) in (Amps) in Pressureper Extruder Frostline 501i Each Extruder Each Extruder (psi) (lb/hr)Height Layflat (wt %) A B C A B C A B C A B C (cm) (cm) C12 0 185 185181 3.0 3.1 4.6 174 172 209 1.9 1.9 2.5 — — 5 186 185 181 2.9 3.0 4.4171 70 204 1.9 1.9 2.5 4.0 23.0 10 185 186 181 2.8 2.9 4.3 170 168 2031.9 1.9 2.5 4.0 23.1 15 185 186 181 2.6 2.8 4.1 163 165 196 1.9 1.9 2.44.0 23.3 30 184 183 183 2.5 2.5 3.8 175 155 185 1.9 1.8 2.4 3.5 23.0 Ex.18 — 0 205 184 184 2.5 2.5 3.7 137 136 161 2.0 1.9 2.5 — — 5 — 184 1842.5 2.4 3.5 136 136 159 2.0 1.9 2.5 — — 10 — 183 183 2.4 2.3 3.5 134 133157 1.9 1.9 2.4 — — 15 184 184 184 2.3 2.3 3.3 129 131 154 2.0 1.9 2.54.0 23.5 30 183 184 184 2.2 2.2 3.1 123 123 144 1.9 1.9 2.4 3.0 23.5 C130 186 186 186 3.6 3.7 5.2 192 189 226 2.0 2.1 2.6 — — 5 186 185 185 3.53.6 5.0 187 186 220 2.0 2.0 2.5 4.5 23.5 10 185 186 186 3.3 3.5 4.7 182180 214 2.0 2.0 2.5 4.5 23.5 15 186 185 185 3.1 3.3 4.5 178 177 210 1.92.0 2.5 4.5 23.5 30 185 184 184 3.0 2.9 3.9 170 157 188 1.9 1.9 2.3 4.023.3 Ex. 19 0 184 186 186 2.8 2.8 4.1 146 146 174 2.0 2.0 2.5 — — 5 183185 185 2.7 2.8 4.0 144 144 169 2.0 2.0 2.5 — 23.4 10 183 184 184 2.62.7 3.8 142 143 167 2.0 2.0 2.5 4.0 23.4 15 183 183 183 2.7 2.8 3.7 142141 167 2.0 1.9 2.5 4.0 23.5 30 184 184 184 2.6 2.5 3.4 137 137 156 2.01.9 2.4 3.5 23.5

The terms “processibility of a polymer” and “polymer processibility” areused interchangeably and refer to the ability to maximize productionrate. As such, a highly processable polymer is capable of beingconverted at a higher rate than a polymer with less processibility.Extrusion processibility can be limited, for example, by the limit ofthe drive motor (measured as power consumption in Amps) and the pressurebuild up within the extruder at various locations including at theentrance to the die. In blown film processes, the maximum productionrate can also be limited by the stability of the bubble. It will beunderstood by those skilled in the art that there are many forms ofbubble instability any of which can limit the maximum production rateeven if the extruder system is capable of higher throughput with theparticular polymer or polymer blend involved. In demonstrating theadvantages of the inventive polyethylenes, the minimum air-ring air flowrequired to maintain a stable bubble for at least five seconds at atake-off rate providing 12.5 μm (0.5 mil) film was measured. A lowerminimum air flow is indicative of a more stable bubble. The inventivepolyethylenes had improved processibility over the comparativepolyethylenes, some of which are shown in Table 8.

TABLE 8 Blown film experiment Blend Bubble Stability Composition -Extruder data Min air flow for LDPE 501i Motor Load Pressure stablebubble at 12.5 (wt %) (Amps) (psi) μm (% of max flow) C12 0 10.7 209 435 10.3 204 42 10 10.0 203 41 15 9.5 196 41 30 8.8 185 39 Ex. 18 0 8.7161 41 5 8.4 159 40 10 8.2 157 39 15 7.9 154 41 30 7.5 144 38 C13 0 12.5226 43 5 12.1 220 44 10 11.5 214 44 15 10.9 210 43 30 9.8 188 41 Ex. 190 9.7 174 42 5 9.5 169 42 10 9.1 167 42 15 9.2 167 42 30 8.5 156 41

For all polymers that included the addition of the LDPE 501i a reducedmotor load was expected with respect to the pure polyethylene. Both ofExamples 18 and 19 had a lower motor load than the comparative examplesC12 and C13, respectively, at all levels of added LDPE 501i whencomparing equal blend compositions. Surprisingly and unexpectedly, thepure polyethylenes of Examples 18 and 19, i.e., no LDPE was added, alsoexhibited less motor load than the comparative examples blended with anylevel of LDPE 501i up to and including 30 wt % LDPE 501i in spite of theLDPE 501i having a melt index of 1.85 g/10 min.

Both of Examples 18 and 19 exhibited a substantially lower extruderpressure than the comparative examples C12 and C13, respectively, at alllevels of added LDPE 501i when comparing equal blend compositions.Surprisingly and unexpectedly, the pure polyethylenes of Examples 18 and19, i.e., no LDPE was added, also exhibited substantially less extruderpressure than the comparative examples blended with any level of LDPE501i up to and including 30 wt % LDPE 501i in spite of the LDPE 501ihaving a melt index of 1.85 g/10 min.

Both of Examples 18 and 19 exhibited a greater or similar bubblestability than the comparative examples C12 and C13 respectively at alllevels of added LDPE 501i when comparing equal blend compositions.Surprisingly and unexpectedly, the pure polyethylenes of Examples 18 and19, i.e., no LDPE was added, exhibited improved bubble stabilitycompared to the comparative resins blended with up to 15% LDPE 501i.

Taken individually and together these results demonstrate that theinventive polyethylenes of Examples 18 and 19 have substantiallysuperior processibility compared to conventional Ziegler-Natta resinsand allow the converter to maintain or increase throughput without theadded cost of obtaining and handling LDPE commonly used to improve theprocessibility of conventional Ziegler-Natta LLDPE. Althoughdemonstrated here for blown film production, it is expected that thesebenefits will equally apply to any conversion process involving theextrusion of polymer, including, but limited to, cast processes, e.g.,cast film and extrusion coating, injection molding, blow-molding, andsheet extrusion. In particular, the ability to eliminate or reduce theuse of LDPE and yet maintain or increase processibility is highlyadvantageous as it is well known in the art that LDPE added toZiegler-Natta LLDPE generally reduces the physical properties comparedto the pure Ziegler-Natta resin. To compensate for this, converters willoften increase the gauge of the film thus reducing the benefits of theincreased production rate obtained through the addition of LDPE.

Tensile properties of Examples 18 and 19 and comparative examples C12and C13 and blends with LDPE 501i are shown in Table 9 below. Themeasured tensile properties were Elmendorf Tear in machine direction(MD) and cross direction (CD) with respect to film take-off directionand puncture. These properties were measured for both the 25 μm and the12.5 μm films.

TABLE 9 Physical Properties of Films Tested Film gauge: 25 μm Filmgauge: 12.5 μm Blend Elmendorf Elmendorf Composition - Puncture TearPuncture Tear LDPE 501i Force CD MD Force CD MD (wt %) (ft · lb/in3) (g)(g) (ft · lb/in3) (g) (g) C12 0 218 541 406 209 277 582 5 171 533 344177 301 674 10 172 567 270 179 300 672 15 148 578 210 137 311 726 30 128585 161 111 309 684 Ex. 18 0 160 467 106 145 364 823 5 150 518 108 138346 769 10 120 556 66 127 401 913 15 122 516 106 113 424 1025 30 104 561100 97 379 975 C13 0 216 305 155 215 253 559 5 188 325 147 168 229 49110 175 369 103 154 258 568 15 155 380 90 131 266 585 30 108 372 51 106212 468 Ex. 19 0 134 338 97 121 244 537 5 121 366 76 112 249 567 10 101390 58 105 275 607 15 92 362 54 101 277 647 30 86 428 79 292 675

Puncture is reported as puncture force (foot pounds per cubic inch orft·lb/in³). In all examples, the puncture of the pure polyethylene filmsof Examples 18 and 19, i.e., no LDPE 501i was added, was less than thepure comparative resins, but the puncture of the pure inventive resinsexceeds the blends of comparative resins containing about 20% or moreLDPE 501i.

Some observations between the puncture of the ethylene/hexene copolymerfilms of Ex. 18 and C12 were as follows. The 25 μm pure polyethylenefilm of Ex. 18 had superior puncture to the 25 μm thick comparative filmof C12 that contained 15 wt % LDPE 501i. The Ex. 18 film with 5 wt %LDPE had the same puncture as the C12 film that contained 15% LDPE. The12.5 μm pure polyethylene film of Ex. 18 had superior puncture to thecomparative resin C12 containing 15 wt % LDPE 501i. The Ex. 18 film with5 wt % LDPE had the same puncture as C12 containing 15 wt % LDPE. Toachieve equivalent motor load to the pure polyethylene film of Ex. 18,30 wt % LDPE 501i loading in the comparative example C12 was required.An even greater amount of LDPE 501i would be required to achieveequivalent extruder pressure. Accordingly, through the use of theinventive polyethylene of Ex. 18 it was possible to achieve improvedpuncture performance while at the same time enjoying the benefits ofincreased processibility.

Some observations between the puncture of the ethylene/butene copolymerfilms of Ex. 19 and C13 were as follows. The 25 μm pure polyethylenefilm of Ex. 19 had superior puncture to the comparative resin C13 thatcontained 30 wt % LDPE 501i and via interpolation, similar puncture to a22 wt % blend. The film of Ex. 19 that contained 5 wt % LDPE hadsuperior puncture compared to the film of C13 that contained 30 wt %LDPE. The 12.5 μm pure polyethylene film of Ex. 19 had superior punctureto the comparative C13 film that contained 30 wt % LDPE 501i. The filmof Ex. 19 that contained 10 wt % LDPE had the same puncture as the filmof C13 that contained 30 wt % LDPE. To achieve equivalent motor load tothe pure polyethylene film of Ex. 19, 30 wt % LDPE 501i loading incomparative example C13 was required. An even greater amount of LDPE501i would be required to achieve equivalent extruder pressure.Accordingly, through the use of the inventive polyethylene of Ex. 19 itwas possible to achieve improved puncture performance while at the sametime enjoying the benefits of increased processibility.

The effect the addition of the LDPE 501i to the tear properties was verydependent on the gauge of film produced under the conditions of theexperiments. At 25 μm, the cross direction tear or CD tear (alsoreferred to as transverse direction or TD tear) increased withincreasing LDPE loading whereas the machine direction or MD teardecreased. In contrast, at 12.5 μm, the CD and MD tear both increasedwith the addition of LDPE up to about 15 wt %. At higher levels the CDand MD tear values tended to decrease slightly. The inventivepolyethylenes of Examples 18 and 19 were found to be particularlysuitable for thin gage film applications requiring good tearperformance.

Some observations between the tear properties of the ethylene/hexenecopolymer films (Ex. 18 vs. C12) were as follows. The CD tear for the 25μm films of Ex. 18 and C12 were substantially the same at all LDPEloadings, including zero loading. With both Ex. 18 and C12, the CD teartended to increase with increased LDPE loading. The MD tear for the 25μm film of Ex. 18 was substantially reduced compared to the purecomparative polyethylene of C12. The MD tear of Ex. 18 was essentiallyunaffected by the level of LDPE loading maintaining a value of about 100g whereas the tear of C12 dropped from about 400 g with zero LDPE toabout 160 g with 30 wt % LDPE. The CD tear of the 12.5 μm film of Ex. 18and all blends of Ex. 18 containing LDPE 501i exceeded the CD tear ofthe comparative films of C13. The CD tear tended to increase withincreasing LDPE composition. The CD tear of Ex. 18 reached a maximum at15 wt % LDPE loading with a value of about 425 g and the maximum tearreached with the C13 films was also at a loading of 15 wt % LDPE with avalue of about 310 g. The MD tear for all of the 12.5 μm films of Ex. 18exceeded the MD tear of the comparative films of C13. For both Ex. 18and C12, the MD tear tended to increase with increasing LDPE loading.The MD tear of Ex. 18 reached a maximum at 15 wt % LDPE loading with avalue of about 1,025 g and the MD tear of C13 also reached a maximum at15 wt % LDPE with a value of about 725 g. The inventivepolyethylene/hexene copolymer of Ex. 19 was particularly advantageouswhen formed into thin gauge film (12.5 μm) by the blown film process.Indeed, not only were the CD and MD tear properties of the purepolyethylene of Ex. 18 substantially improved compared to C12 at anyLDPE 501i loading, the inventive polyethylene copolymer of Ex. 18, inthe absence of LDPE provided superior processibility. The purepolyethylene copolymer of Ex. 18, i.e., no LDPE was added, was lessadvantageous at the thicker gauge (25 μm); however, in situations wherea converter uses a high loading of LDPE (e.g., 15 wt % or more) then thepure polyethylene copolymer of Ex. 18 would provide similar CD and MDtear properties with superior processibility.

Some observations between the tear properties of the ethylene/butenecopolymer films (Ex. 19 vs. C13) were as follows. The CD tear of the 25μm films of the inventive polyethylene copolymer Ex. 19 and thecomparative copolymer C13 were substantially the same at all LDPEloadings, including zero loading. With both Ex. 19 and C13, the CD teartended to increase with increased LDPE loading. The MD tear for the 25μm films for the pure polyethylene copolymer of Ex. 19 was about 100 g,which was lower than the pure comparative resin C13 (about 155 g). TheMD tear for both Ex. 19 and C13 films reduced in an approximately linearfashion when the LDPE was added. The MD tear of the pure Ex. 19 film wasabout the same as that of the C13 film that contained 10 wt % LDPE andwas superior to the C13 films that contained higher levels of LDPE 501i.

The CD tear for the 12.5 μm films for all the polyethylene copolymers ofEx. 19 was substantially the same as that of the comparative C13 filmsup to about 15 wt % LDPE 501i. At 30 wt % LDPE loading the CD tear ofthe Ex. 19 film was about 290 g, while the CD tear of the correspondingC13 film was about 210 g. For both Ex. 19 and C13, the CD tear tended toincrease with increasing LDPE loading. The CD tear of Ex. 19 reached amaximum at 30 wt % LDPE loading with a value of about 290 g, while theCD tear of the C13 film reached a maximum at 15 wt % LDPE loading with avalue of about 265 g.

The MD tear of the Ex. 19 films and the C13 films were about equal atabout 540 g and 560 g respectively. The MD tear of the Ex. 19 filmsincreased in approximately a linear fashion, reaching a value of about675 g at 30 wt % LDPE 501i loading. The MD tear of the C13 films wassubstantially unaffected by the addition of LDPE 501i up to about 15 wt% LDPE. At 30 wt % LDPE loading, however, the C13 films showed asubstantial decrease in MD tear.

The inventive Ex. 19 polyethylene copolymer films were particularlyadvantageous when formed into thin gauge films (12.5 μm, for example) bythe blown film process. The CD and MD tear properties of the purepolyethylene films of Ex. 19 were generally similar to the comparativepolyethylene films of C13 at any LDPE 501i loading, while the inventivepolyethylene copolymer of Ex. 19, in the absence of LDPE loading,provided superior processibility. The inventive polyethylene copolymerof Ex. 19 was also advantageous for the production of thicker gaugefilms (25 μm, for example), especially when compared to the comparativepolyethylene copolymer of C13 at greater than about 10 wt % LDPEloading. In situations where a converter currently uses a high loadingof LDPE (e.g., 10 wt % or more) then the pure polyethylene copolymer ofEx. 19 would provide similar CD and MD tear properties with superiorprocessibility.

Optics (clarity and haze) were also measured for the 25 μm films ofExamples 18 and 19 and comparative examples C12 and C13. The clarity andhaze values are shown in Table 10 below.

TABLE 10 Optics of 1 mil Films Tested Blend Optics testing: B1470 ASTMlab composition - Film gauge: 25 μm LDPE501i Clarity Haze (wt %) (%) (%)C12 0 87.5 12.4 5 89.4 10.2 10 90.6 8.7 15 92.3 7.1 30 94.0 5.5 Ex. 18 095.9 6.0 5 95.2 6.7 10 95.5 6.0 15 95.4 5.7 30 94.7 5.4 C13 0 99.5 4.9 599.5 3.7 10 99.3 3.0 15 99.4 2.6 30 98.1 2.5 Ex. 19 0 98.2 5.2 5 97.45.0 10 97.7 4.6 15 97.4 4.5 30 96.2 5.0

The clarity values shown in Table 10 are reported as the percentage ofincident light. The clarity and haze values were measured according toASTM D1746 and D1003, respectively. The clarity of all inventivepolyethylene copolymer Ex. 18 films exceeded the clarity of allcorresponding comparative C12 films. The clarity of the C12 filmsincreased from 87.5% to 94.0% as LDPE loading was increased from zero to30%. The clarity of the Ex. 18 films remained substantially unchanged asthe LDPE loading was increased, with a value close to 95.5% in allcases.

The clarity for both inventive and comparative ethylene/butene copolymerfilms of Ex. 19 and C13 were substantially unchanged at all loadings ofLDPE 501i. The clarity of the pure polyethylene copolymer of Ex. 19 wasabout 98.2% and that of the pure copolymer of C13 was about 99.5%.

The haze of all inventive polyethylene copolymer films of Ex. 18 wasless than the haze of the corresponding comparative films of C12. Thehaze of the comparative C13 films decreased from 12.4% to 5.5% as theLDPE loading increased from zero to 30 wt %. The haze of the inventivepolyethylene copolymer of Ex. 18 was substantially unchanged by additionof LDPE, with a value of about 6% for pure Ex. 18 and about 5.4% for the30 wt % LDPE loading.

The haze for the Ex. 19 films remained substantially unchanged at allloadings of LDPE 501i with a value close to about 5%. The haze for theC13 films decreased with increased loading of LDPE 501i from 4.9% to2.5%.

The optics of the inventive ethylene/hexene copolymer of Ex. 18 wassuperior to the optics of the comparative ethylene/hexene copolymer ofC13 and in particular was superior to the optics of the comparativecopolymer containing up to 30 wt % LDPE 501i. This, in addition to thesuperior processibility of the inventive resins indicates the inventivecopolymer of Ex. 18 would be advantageous in situations where goodoptics are required.

Additional Polymerization Experiments

A third and a fourth batch of the same catalyst used to produce thepolymers of Examples 1-9 and Examples 16-19 were prepared and were usedto produce the polymers of Examples 20-25 and 26-32, respectively. Thesethird and fourth batches of catalyst were prepared according to the samegeneral procedure as outlined above for the first batch for Examples 1-9and 16-19, with minor changes that would be obvious to the skilledperson in view of Table 11 below. As such, these catalysts were alsoprepared without the addition of any electron donors as discussed anddescribed above and these catalysts can also be referred to as a “donorfree catalysts.” These catalysts were analyzed for Ti, Mg, and content,the results of which are shown in Table 11 below.

TABLE 11 Cl⁻ Mg Ti Catalyst (mmol/g) (mmol/g) (mmol/g) Mg/Ti Used to4.38 1.50 0.949 1.58 Produce the Polymers of Examples 20-25 Used to 4.671.49 0.804 1.85 Produce the Polymers of Examples 26-32

A gas phase fluidized bed polymerization reactor of the UNIPOL™ PEProcess design having a nominal diameter of about 35.6 cm (about 14inches) was used for the continuous production of both linear lowdensity polyethylene (LLDPE), medium density polyethylene (MDPE), andhigh density polyethylene (HDPE). The polymerization process was asgenerally described above for Examples 1-19. The polymer of ComparativeExample C18 was produced using UCAT™ A4520 Catalyst, available fromUnivation Technologies, LLC.

The polymerization conditions and results for the production of thepolymers of Examples 20-32 is shown in Tables 12A-B below.

TABLE 12A Examples C18 Ex. 20 Ex. 21 Ex. 22 Ex. 23 Ex. 24 Polymer TypeLLDPE LLDPE LLDPE LLDPE LLDPE LLDPE Catalyst Ti Content (wt %) * 4.544.54 4.54 4.54 4.54 Catalyst Al Content (wt %) * 0.11 0.11 0.11 0.110.11 Catalyst Mg Content (wt %) * 3.64 3.64 3.64 3.64 3.64 Prod Rate(lbs/hr) 43.3  36.0 35.3 37.3 32.5 37.5 Residence Time (hrs) 2.6  2.62.6 2.4 2.8 2.8 C₂ Partial Pressure (psia) 100.00  80.32 80.48 80.2679.85 80.05 H₂/C₂ (m/m)  0.130 0.102 0.114 0.134 0.0905 0.128 C₄/C₂Conc. Ratio (m/m)  0.374 0.328 0.336 0.342 0.322 0.000 C₆/C₂ Conc. Ratio(m/m)  0.000 0.000 0.000 0.000 0.000 0.142 H₂/C₂ Mass Feed Ratio(mlb/lb) 1.16 0.902 1.05 1.07 0.824 0.975 C₄/C₂ Mass Feed Ratio (lb/lb) 0.130 0.126 0.124 0.126 0.129 — C₆/C₂ Mass Feed Ratio (lb/lb) — — — — —0.140 Isopentane (mole %) 0.48 3.17 2.35 2.19 3.00 2.62 RX Pressure(psig) 355.5   355.5 355.6 355.2 355.3 355.7 RX Temperature (° C.) 88.0 88.0 88.0 88.0 88.0 88.0 Gas Velocity (ft/sec) 1.82 1.71 1.72 1.71 1.691.68 Bed Weight (lbs) 114    94 90 90 91 105 Fluid Bulk Density (lb/ft³)14.96  11.04 11.02 11.49 10.26 13.70 Co-catalyst ID TEAl TEAl TEAl TEAlTEAl TEAl Co-catalyst Conc. (wt %) 2.5  1.0 1.0 1.0 1.0 1.0 Co-catalystFeed (cc/hr) 288.7   154.2 73.6 36.3 330.5 80.9 Reactor Co-catalystConc. - 228    59 28 13 139 29 Prod. Rate Basis (ppmw) Cont. Additive NoYes Yes Yes Yes Yes Continuity Additive Conc. (wt %) 0   20 20 20 20 20Continuity Additive Feed (cc/hr) 0.00 1.00 1.00 1.00 1.00 1.00 ReactorCont. Additive 0.00 10.41 10.61 10.04 11.53 9.99 Conc. - Prod Rate Basis(ppmw) Cat. Prod. - Ti ICPES Basis 5,152¹     9,660 14,459 16,157 6,54211,407 (g PE/g Catalyst) I₂ Melt Index (dg/min) 1.07 0.95 0.78 0.71 0.900.70 MFR, I₂₁/I₂ 24.8  39.1 42.7 48.9 37.3 71.3 Polymer Density (g/cc) 0.918 0.918 0.918 0.918 0.918 0.918 ≧C₄ Branch ²/1000 C. — 0.049 0.0530.056 0.046 — * UCAT ™ A4520 Catalyst available from UnivationTechnologies, LLC. ¹Estimated by material balance rather than Ti ICPESBasis. ² Branches four carbons or longer.

TABLE 12B Examples Ex. 25 Ex. 26 Ex. 27 Ex. 28 Ex. 29 Ex. 30 Ex. 31 Ex.32 Polymer Type LLDPE LLDPE MDPE HDPE HDPE HDPE HDPE HDPE Catalyst TiContent (wt %) 3.85 3.85 3.85 3.85 3.85 3.85 3.85 3.85 Catalyst AlContent (wt %) 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 Catalyst MgContent (wt %) 3.62 3.62 3.62 3.62 3.62 3.62 3.62 3.62 Prod Rate(lbs/hr) 36.0 36.6 39.0 36.3 33.0 33.0 38.8 34.0 Residence Time (hrs)3.0 2.6 3.3 3.0 2.5 2.7 2.8 2.9 C₂ Partial Pressure (psia) 79.95 79.9180.75 120.12 120.06 120.32 118.90 120.61 H₂/C₂ (m/m) 0.147 0.130 0.1520.553 0.098 0.213 0.172 0.098 C₄/C₂ Conc. Ratio (m/m) 0.000 0.000 0.0000.000 0.025 0.016 0.013 0.000 C₆/C₂ Conc. Ratio (m/m) 0.147 0.146 0.1140.046 0.000 0.000 0.000 0.0085 H₂/C₂ Mass Feed Ratio (mlb/lb) 1.10 0.9801.08 8.00 1.22 2.55 2.13 1.55 C4/C₂ Mass Feed Ratio (lb/lb) — — — —0.0142 0.0107 0.0091 — C₆/C₂ Mass Feed Ratio (lb/lb) 0.141 0.143 0.09910.046 — — — 0.0105 Isopentane (mole %) 2.49 2.73 2.82 1.91 2.30 2.161.85 1.61 RX Pressure (psig) 355.9 355.7 355.4 355.9 356.1 356.2 354.4344.8 RX Temperature (° C.) 88.0 88.0 80.8 102.0 102.0 102.0 102.1 101.9Gas Velocity (ft/sec) 1.64 1.59 1.61 1.69 1.70 1.74 1.75 1.87 Bed Weight(lbs) 103 104 106 91 97 109 99 102 Fluid Bulk Density (lb/ft³) 13.8413.51 14.32 11.09 14.21 16.19 12.68 11.96 Co-catalyst ID TEAl TEAl TEAlTEAl TEAl TEAl TEAl TEAl Co-catalyst Conc. (wt %) 1.0 1.0 1.0 1.0 1.01.0 1.0 1.0 Co-catalyst Feed, (cc/hr) 40.0 80.0 80.9 35.0 50.5 53.2160.9 90.7 Reactor Co-catalyst Conc. - 15 30 28 13 21 22 57 36 Prod.Rate Basis (ppmw) Cont. Additive Yes Yes Yes Yes Yes Yes Yes YesContinuity Additive Conc. (wt %) 20 20 20 20 20 20 20 20 ContinuityAdditive Feed (cc/hr) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 2.50 Reactor Cont.Additive 10.41 10.25 9.61 10.32 11.36 11.36 9.65 27.56 Conc. - Prod RateBasis (ppmw) Cat. Prod. - Ti ICPES 10,462 10,026 11,257 17,265 8,4436,863 5,224 10,577 Basis (g PE/g Catalyst) I₂ Melt Index (dg/min) 0.770.90 0.83 24.93 0.27 0.99 1.05 0.23 MFR, I₂₁/I₂ 71.5 68.3 56.5 31.6 41.845.1 38.3 40.3 Polymer Density (g/cc) 0.917 0.919 0.926 0.953 0.9460.954 0.954 0.951 ≧C₄ Branch ¹/1000 C. — — — — — 0.058 0.043 — ¹Branches four carbons or longer.

Selected properties for the polymers of Examples 20-32 are shown inTables 13A-B below.

TABLE 13A Como- MI Density MS ≧C₄ Branch¹/ Ex. Type nomer (I₂) (g/cm₃)(cN) 1000 C. C18 LLDPE Butene 1.07 0.918 2.9 —* Ex. 20 LLDPE Butene 0.950.918 5.7 0.049 Ex. 21 LLDPE Butene 0.78 0.918 7.2 0.053 Ex. 22 LLDPEButene 0.71 0.918 8.1 0.056 Ex. 23 LLDPE Butene 0.90 0.918 5.3 0.046 Ex.24 LLDPE Hexene 0.70 0.918 7.8 —* Ex. 25 LLDPE Hexene 0.77 0.917 8.5 —*Ex. 26 LLDPE Hexene 0.90 0.919 6.4 —* Ex. 27 MDPE Hexene 0.83 0.926 10.2—* Ex. 28 HDPE Hexene 24.93 0.953 2.2 —* Ex. 29 HDPE Butene 0.27 0.94616.0 —* Ex. 30 HDPE Butene 0.99 0.954 10.6 0.058 Ex. 31 HDPE Butene 1.050.954 7.3 0.043 Ex. 32 HDPE Hexene 0.23 0.951 14.1 —* ¹Branches fourcarbons or longer. *Value was not measured.

TABLE 13B Como- M_(w) (Da, RI M_(w) (Da, LS MWD (RI MWD (LS Mw (LS)/ Ex.Type nomer Detector¹) Detector²) Detector) Detector) Mw (RI) C18 LLDPEButene 115,325 127,826 3.98 4.43 1.11 Ex. 20 LLDPE Butene 122,929180,402 5.58 7.46 1.47 Ex. 21 LLDPE Butene 123,322 185,595 5.39 7.431.50 Ex. 22 LLDPE Butene 125,605 196,961 5.62 7.92 1.57 Ex. 23 LLDPEButene 125,548 181,811 6.29 7.94 1.45 Ex. 24 LLDPE Hexene 128,928202,948 6.21 8.74 1.57 Ex. 25 LLDPE Hexene 126,727 213,203 7.12 10.411.68 Ex. 26 LLDPE Hexene 123,659 192,221 6.69 9.18 1.55 Ex. 27 MDPEHexene 114,092 188,634 6.02 8.80 1.65 Ex. 28 HDPE Hexene 53,997 146,8075.99 13.90 2.72 Ex. 29 HDPE Butene 140,390 223,984 5.30 7.12 1.60 Ex. 30HDPE Butene 101,800 177,166 5.90 9.09 1.74 Ex. 31 HDPE Butene 109,748181,933 5.27 7.77 1.66 Ex. 32 HDPE Hexene 157,361 237,391 5.70 7.85 1.51¹Refractive index detector. ²Light scattering detector.

Without wishing to be bound by theory, it is believed that the ratio ofthe M_(w) calculated using the LS light scattering detector to the M_(w)calculated using the RI refractive index detector, M_(w) (LS)/M_(w)(RI), is related to the long chain branching present in the polymer. Thepolyethylene can have a M_(w) (LS)/M_(w) (RI) value of from about 1.4 toabout 3.0, from about 1.4 to 2.8, or from about 1.45 to 2.72.

FIG. 6 depicts a graphical representation of the polymer Long ChainBranching (LCB) for the LLDPE polymers of Examples 20 through 23 versusthe concentration of co-catalyst (TEA′) used in forming the polymer. Asseen in FIG. 6, as the concentration of the TEAl co-catalyst decreases(given in ppm_(w)—parts per million weight) the LCB for the LLDPEpolymer increases. Referring now to FIG. 7, there is seen a graphicalrepresentation of the polymer MFR (Melt Flow Ratio) I₂₁/I₂ versus theconcentration of co-catalyst for the LLDPE polymers of Example 20through Example 23. Again, as the concentration of the TEAl co-catalystdecreases the MFR for the LLDPE polymer increases. The same trend isrepeated with the association between the electron donor-freeZiegler-Natta catalyst productivity versus the concentration ofco-catalyst in the LLDPE polymers for Example 20 through Example 23, asseen in FIG. 8. Using these surprising results it is then possible toprovide a relationship between the LCB versus the polymer MFR (I₂₁/I₂)for the LLDPE of Examples 20 through Example 23 as seen in FIG. 9.

The same surprising trend seen for the LLDPE of Examples 20 through 23is also seen for the HDPE of Examples 30 and 31. As seen in FIGS. 10through 13, as the concentration of the TEAl co-catalyst decreases theMFR for the HDPE polymer increases. The same trend is repeated with theassociation between the electron donor-free Ziegler-Natta catalystproductivity versus the concentration of co-catalyst in the HDPEpolymers for Example 30 and Example 31, as seen in FIG. 12. Using thesesurprising results it is then possible to provide a relationship betweenthe LCB versus the polymer MFR (I₂₁/I₂) for the HDPE for Example 30 and31, as seen in FIG. 13.

FIG. 14 and FIG. 15 provide a further association between the polymerLCB and the electron donor-free Ziegler-Natta catalyst productivity forExample 20 through Example 23 (FIG. 14) and for Example 30 and Example31 (FIG. 15). Using such associations, the catalyst productivity,particularly the material balance catalyst productivity, can be used torapidly provide LCB information during the production of LLDPE and/orHDPE as provided herein.

So, it becomes apparent that the LCB relates to the MFR and to theproductivity, where each of these properties can be related back to thealkyl aluminum co-catalyst concentration used in producing the polymerin a predetermined relationship. Using this predetermined relationship,the amount of LCB of the polyethylene can be determined from thepolymerization reactor using the measured MFR (I₂₁/I₂). Measurableparameters such as the MFR and/or productivity can then be used inessentially real time during polymer production as an indication of theLCB for the polymer. This relationship can then lead to better processcontrol of the polymerization process, where an amount of the LCB can becontrolled and/or adjusted by controlling the MFR through control ofand/or changes to the amount of co-catalyst (TEAl) in the polymerizationreactor.

All numerical values are “about” or “approximately” the indicated value,and take into account experimental error and variations that would beexpected by a person having ordinary skill in the art.

Various terms have been defined above. To the extent a term used in aclaim is not defined above, it should be given the broadest definitionpersons in the pertinent art have given that term as reflected in atleast one printed publication or issued patent. Furthermore, allpatents, test procedures, and other documents cited in this applicationare fully incorporated by reference to the extent such disclosure is notinconsistent with this application and for all jurisdictions in whichsuch incorporation is permitted.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention can be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow. Such embodiments include thefollowing:

Embodiment 1 includes a polymerization method, comprising: performing apolymerization reaction in a polymerization reactor to producepolyethylene, wherein the polymerization reaction is catalyzed by anelectron donor-free Ziegler-Natta catalyst and an alkyl aluminumco-catalyst with ethylene and optionally one or more comonomers toproduce the polyethylene; removing a portion of the polyethylene fromthe polymerization reactor; measuring a melt flow ratio (I₂₁/I₂) of thepolyethylene removed from the polymerization reactor; and determining anamount of long chain branching (LCB) of the polyethylene from thepolymerization reactor using the measured melt flow ratio and apredetermined relationship between the melt flow ratio (I₂₁/I₂) and theLCB. In Embodiment 2, the polymerization method of embodiment 1 furtherincludes adjusting a weight concentration of the alkyl aluminumco-catalyst present in the polymerization reactor to control the LCB ofthe polyethylene produced in the polymerization reactor. In Embodiment3, the polymerization process of embodiment 2 provides that decreasingthe weight concentration of the alkyl aluminum co-catalyst present inthe polymerization reactor increases the LCB of the polyethyleneproduced in the polymerization reactor. In Embodiment 4, thepolymerization method of embodiment 2 provides that reducing a weightconcentration of the electron donor-free Ziegler-Natta catalyst when theweight concentration of the alkyl aluminum co-catalyst present in thepolymerization reactor is reduced. In embodiment 5, the polymerizationmethod of embodiment 2 further includes increasing a weightconcentration of the electron donor-free Ziegler-Natta catalyst tomaintain a constant production rate of the polyethylene when the weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor is increased. In embodiment 6, the polymerizationmethod of embodiment 2 provides that adjusting the weight concentrationof the alkyl aluminum co-catalyst present in the polymerization reactoris done by changing a mole ratio of the alkyl aluminum co-catalyst toactive metal in the electron donor-free Ziegler-Natta catalyst. Inembodiment 7, the polymerization method of embodiment 2 provides thatadjusting the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor changes the melt flow ratio(I₂₁/I₂) of the polyethylene from the polymerization reactor. Inembodiment 8, the polymerization method of embodiment 2 provides thatadjusting the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor changes a production rate of thepolyethylene from the polymerization reactor. In embodiment 9, thepolymerization method of embodiment 2 provides that adjusting the weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor changes cycle gas molar ratios of H₂/C₂ andC₄/C₂. In embodiment 10, the polymerization method of embodiment 2provides that adjusting the weight concentration of the alkyl aluminumco-catalyst present in the polymerization reactor changes cycle gasmolar ratios of H₂/C₂ and C₆/C₂. In embodiment 11, the polymerizationprocess control method of embodiment 1 further includes controlling themelt flow ratio (I₂₁/I₂) of the polyethylene from the polymerizationreactor by adjusting one or more of a H₂/C₂ gas mole ratio, H₂/C₂ weightfeed ratio, a C₄ to C₂ co-monomer gas mole ratio or the C₄ to C₂ weightfeed ratio. In embodiment 12, the polymerization method of embodiment 1further includes controlling the melt flow ratio (I₂₁/I₂) of thepolyethylene from the polymerization reactor by adjusting one or more ofa H₂/C₂ gas mole ratio, H₂/C₂ weight feed ratio, a C₆ to C₂ co-monomergas mole ratio or the C₆ to C₂ weight feed ratio. In embodiment 13, thepolymerization method of embodiment 1 further includes varying a weightconcentration of the alkyl aluminum co-catalyst in the polymerizationreactor while performing the polymerization reaction, therebyimplementing a predetermined change in at least the LCB. In embodiment14, the polymerization method of embodiment 13 includes generating meltflow ratio (I₂₁/I₂) data and LCB data from polyethylene produced whilevarying the weight concentration of the alkyl aluminum co-catalyst inthe polymerization reactor; and developing the predeterminedrelationship between the melt flow ratio (I₂₁/I₂) and the LCB from themelt flow ratio (I₂₁/I₂) data and LCB data. In embodiment 15, thepolymerization method of embodiment 1 provides that the weightconcentration of the alkyl aluminum co-catalyst in the polymerizationreactor is adjusted so as to bring the LCB in the polyethylene intocompliance with a predetermined product specification set. In embodiment16, the polymerization method of embodiment 1 further includescontrolling the melt flow ratio (I₂₁/I₂) of the polyethylene from thepolymerization reactor by adjusting the weight concentration of thealkyl aluminum co-catalyst in the polymerization reactor. In embodiment17, the polymerization method of embodiment 1 further includes adjustinga feed rate of the electron donor-free Ziegler-Natta catalyst tomaintain a constant polyethylene production rate and thereforeintroducing catalyst productivity changes from the polymerizationreactor, where deviations in catalyst productivity function as a leadingindicator to impending changes in the polymer MFR and/or LCB. Inembodiment 18, the polymerization method of embodiment 1 furtherincludes decreasing the weight concentration of the alkyl aluminumco-catalyst in the polymerization reactor thereby increasingproductivity of the electron donor-free Ziegler-Natta catalyst relativeto the productivity before the change in weight concentration. Inembodiment 19, the polymerization method of embodiment 1 has thepolyethylene with a LCB of greater than about 0.01 per 1,000 carbonatoms and less than about 0.07 per 1,000 carbon atoms. In embodiment 20,the polymerization method of embodiment 1 has the polyethylene LCBbetween about 0.05 and 0.06 per 1,000 carbon atoms. In embodiment 21,the polymerization method of embodiment 1 has the LCB composed of 4 ormore carbon atoms. In embodiment 22, the polymerization method ofembodiment 1 has the polyethylene with a ratio of weight-averagemolecular weight calculated using a light scattering (LS) detector toweight-average molecular weight calculated using a refractive index (RI)detector, M_(w) (LS)/M_(w) (RI), of from about 1.4 to about 3.0. Inembodiment 23, the polymerization method of embodiment 1 has thepolyethylene with a melt flow ratio (I₂₁/I₂) ranging from about 35 toabout 55. In embodiment 24, the polymerization method of embodiment 1has the polyethylene with a density of from 0.91 g/cm³ to about 0.965g/cm³. In embodiment 25, the polymerization method of embodiment 1provides that the electron donor-free Ziegler-Natta catalyst is formedby a process that comprises: combining one or more supports with one ormore magnesium-containing compounds under reaction conditions to form afirst reacted product; combining one or more chloro substituted silaneswith the first reacted product under reaction conditions to form asecond reacted product; and combining one or more titanium halides withthe second reacted product under reaction conditions to form theelectron donor-free Ziegler-Natta catalyst, wherein the one or moresupports comprises silica, alumina, or a combination thereof, whereinthe one or more magnesium-containing compounds has the formula:R¹—Mg—R², wherein R¹ and R² are independently selected from the groupconsisting of hydrocarbyl groups and halogen atoms. In embodiment 26,the polymerization method of embodiment 1 includes selecting thepolymerization reactor from the group consisting of a solution reactor,a slurry loop reactor, a supercritical loop reactor, a stirred-bedgas-phase reactor, or a fluidized-bed, gas-phase reactor. In embodiment27, the polymerization method of embodiment 1 has the alkyl aluminumco-catalyst selected from triethylaluminum (TEAl), triisobutylaluminum,tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum,trimethylaluminum, or any combination thereof. In embodiment 28, thepolymerization process control method of embodiment 27 has the alkylaluminum co-catalyst being the TEAl co-catalyst.

Embodiment 29 is a polymerization process control method that includes:performing a polymerization reaction in a polymerization reactor toproduce polyethylene, wherein the polymerization reaction is catalyzedby an electron donor-free Ziegler-Natta catalyst and an alkyl aluminumco-catalyst with ethylene and optionally one or more comonomers toproduce the polyethylene; removing a portion of the polyethylene fromthe polymerization reactor; measuring a melt flow ratio (I₂₁/I₂) of thepolyethylene removed from the polymerization reactor to determine theamount of long chain branching (LCB) using a predetermined relationshipbetween the melt flow ratio (I₂₁/I₂) and the LCB; and controlling anamount of long chain branching (LCB) of the polyethylene from thepolymerization reactor by adjusting a weight concentration of the alkylaluminum co-catalyst present in the polymerization reactor. Inembodiment 30, the polymerization process control method of embodiment29 provides that controlling the amount of LCB includes decreasing theweight concentration of the alkyl aluminum co-catalyst present in thepolymerization reactor to increase the LCB of the polyethylene producedin the polymerization reactor. In embodiment 31, the polymerizationprocess control method of embodiment 29 includes reducing a weightconcentration of the electron donor-free Ziegler-Natta catalyst when theweight concentration of the alkyl aluminum co-catalyst present in thepolymerization reactor is reduced. In embodiment 32, the polymerizationprocess control method of embodiment 29 includes increasing a weightconcentration of the electron donor-free Ziegler-Natta catalyst tomaintain a constant production rate of the polyethylene when the weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor is increased. In embodiment 33, thepolymerization process control method of embodiment 29 provides thatadjusting the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor is done by changing a mole ratioof the alkyl aluminum co-catalyst to active metal in the electrondonor-free Ziegler-Natta catalyst. In embodiment 34, the polymerizationprocess control method of embodiment 29 provides that adjusting theweight concentration of the alkyl aluminum co-catalyst present in thepolymerization reactor changes the melt flow ratio (I₂₁/I₂) of thepolyethylene from the polymerization reactor. In embodiment 35, thepolymerization process control method of embodiment 29 provides thatadjusting the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor changes a production rate of thepolyethylene from the polymerization reactor. In embodiment 36, thepolymerization process control method of embodiment 29 provides thatadjusting the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor changes cycle gas molar ratios ofH₂/C₂ and C₄/C₂. In embodiment 37, the polymerization process controlmethod of embodiment 29 provides that adjusting the weight concentrationof the alkyl aluminum co-catalyst present in the polymerization reactorchanges cycle gas molar ratios of H₂/C₂ and C₆/C₂. In embodiment 38, thepolymerization process control method of embodiment 29 further includescontrolling the melt flow ratio (I₂₁/I₂) of the polyethylene from thepolymerization reactor by adjusting one or more of a H₂/C₂ gas moleratio, H₂/C₂ weight feed ratio, a C₄ to C₂ co-monomer gas mole ratio orthe C₄ to C₂ weight feed ratio. In embodiment 39, the polymerizationprocess control method of embodiment 29 further includes controlling themelt flow ratio (I₂₁/I₂) of the polyethylene from the polymerizationreactor by adjusting one or more of a H₂/C₂ gas mole ratio, H₂/C₂ weightfeed ratio, a C₆ to C₂ co-monomer gas mole ratio or the C₆ to C₂ weightfeed ratio. In embodiment 40, the polymerization process control methodof embodiment 29 further includes varying a weight concentration of thealkyl aluminum co-catalyst in the polymerization reactor whileperforming the polymerization reaction, thereby changing the melt flowratio (I₂₁/I₂) of the polyethylene from the polymerization reactor tomake a predetermined change in at least the LCB or to bring the LCB inthe polyethylene into compliance with a predetermined productspecification set. In embodiment 41, the polymerization process controlmethod of embodiment 40 further includes generating melt flow ratio(I₂₁/I₂) data and LCB data from polyethylene produced while varying theweight concentration of the alkyl aluminum co-catalyst in thepolymerization reactor; and developing the predetermined relationshipbetween the melt flow ratio (I₂₁/I₂) and the LCB from the melt flowratio (I₂₁/I₂) data and LCB data. In embodiment 42, the polymerizationprocess control method of embodiment 29 provides that the weightconcentration of the alkyl aluminum co-catalyst in the polymerizationreactor is adjusted so as to bring the LCB in the polyethylene intocompliance with a predetermined product specification set and/or tocontrol the melt flow ratio (I₂₁/I₂) of the polyethylene from thepolymerization reactor. In embodiment 43, the polymerization processcontrol method of embodiment 29 further includes adjusting a feed rateof the electron donor-free Ziegler-Natta catalyst to maintain a constantpolyethylene production rate from the polymerization reactor, wheredeviations in catalyst productivity function as a leading indicator toimpending changes in the polymer MFR and/or LCB. In embodiment 44, thepolymerization process control method of embodiment 29 further includesdecreasing the weight concentration of the alkyl aluminum in thepolymerization reactor thereby increasing productivity of the electrondonor-free Ziegler-Natta catalyst relative to the productivity beforethe change in weight concentration. In embodiment 45, the polymerizationprocess control method of embodiment 29 provides that the polyethylenehas LCB greater than about 0.01 per 1,000 carbon atoms and less thanabout 0.07 per 1,000 carbon atoms. In embodiment 46, the polymerizationprocess control method of embodiment 29 provides that the polyethylenehas LCB between about 0.05 and 0.06 per 1,000 carbon atoms. Inembodiment 47, the polymerization process control method of embodiment29 provides that the LCB is composed of 4 or more carbon atoms. Inembodiment 48, the polymerization process control method of embodiment29 provides that the polyethylene has a ratio of weight-averagemolecular weight calculated using a light scattering (LS) detector toweight-average molecular weight calculated using a refractive index (RI)detector, M_(w) (LS)/M_(w) (RI), of from about 1.4 to about 3.0. Inembodiment 49, the polymerization process control method of embodiment29 provides that the polyethylene has a melt flow ratio (I₂₁/I₂) rangingfrom about 35 to about 55 or a density of from 0.91 g/cm³ to about 0.965g/cm³. In embodiment 50, the polymerization process control method ofembodiment 29 provides that the electron donor-free Ziegler-Nattacatalyst is formed by a process that includes combining one or moresupports with one or more magnesium-containing compounds under reactionconditions to form a first reacted product; combining one or more chlorosubstituted silanes with the first reacted product under reactionconditions to form a second reacted product; and combining one or moretitanium halides with the second reacted product under reactionconditions to form the electron donor-free Ziegler-Natta catalyst,wherein the one or more supports comprises silica, alumina, or acombination thereof wherein the one or more magnesium-containingcompounds has the formula: R¹—Mg—R², wherein R¹ and R² are independentlyselected from the group consisting of hydrocarbyl groups and halogenatoms. In embodiment 51, the polymerization process control method ofembodiment 29 provides that the polymerization reactor is selected fromthe group consisting of a solution reactor, a slurry loop reactor, asupercritical loop reactor, a stirred-bed gas-phase reactor, or afluidized-bed, gas-phase reactor. In embodiment 52, the polymerizationprocess control method of embodiment 29 provides that the alkyl aluminumco-catalyst is selected from triethylaluminum (TEAl),triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-noctylaluminum, trimethylaluminum, or any combination thereof. Inembodiment 53, the polymerization process control method of embodiment29 provides the alkyl aluminum co-catalyst is the TEAl co-catalyst.

Embodiment 54 is a polymerization process control method that includesperforming a polymerization reaction in a polymerization reactor toproduce polyethylene, where the polymerization reaction is catalyzed byan electron donor-free Ziegler-Natta catalyst and an alkyl aluminumco-catalyst with ethylene to produce the polyethylene; measuring anelectron donor-free Ziegler-Natta catalyst productivity of thepolyethylene from the polymerization reactor; and determining an amountof long chain branching (LCB) of the polyethylene from thepolymerization reactor using the measured electron donor-freeZiegler-Natta catalyst productivity and a predetermined relationshipbetween the electron donor-free Ziegler-Natta catalyst productivity andthe LCB. In embodiment 55, the polymerization process control method ofembodiment 54 further includes adjusting a weight concentration of thealkyl aluminum co-catalyst present in the polymerization reactor tocontrol the LCB of the polyethylene produced in the polymerizationreactor. In embodiment 56, the polymerization process control method ofembodiment 55 provides that decreasing the weight concentration of thealkyl aluminum co-catalyst present in the polymerization reactorincreases the LCB of the polyethylene produced in the polymerizationreactor. In embodiment 57, the polymerization process control method ofclaim 55 includes reducing a weight concentration of the electrondonor-free Ziegler-Natta catalyst when the weight concentration of thealkyl aluminum co-catalyst present in the polymerization reactor isreduced. In embodiment 58, the polymerization process control method ofclaim 55 includes increasing a weight concentration of the electrondonor-free Ziegler-Natta catalyst to maintain a constant production rateof the polyethylene when the weight concentration of the alkyl aluminumco-catalyst present in the polymerization reactor is increased, whereadjusting the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor is done by changing a mole ratioof the alkyl aluminum co-catalyst to active metal in the electrondonor-free Ziegler-Natta catalyst or where adjusting the weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor changes the melt flow ratio (I₂₁/I₂) of thepolyethylene from the polymerization reactor. In embodiment 59, thepolymerization process control method of claim 55 provides thatadjusting the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor changes a production rate of thepolyethylene from the polymerization reactor. In embodiment 60, thepolymerization process control method of claim 55 provides thatadjusting the weight concentration of the alkyl aluminum co-catalystpresent in the polymerization reactor changes cycle gas molar ratios ofH₂/C₂ and C₄/C₂. In embodiment 61, the polymerization process controlmethod of claim 55 provides that adjusting the weight concentration ofthe alkyl aluminum co-catalyst present in the polymerization reactorchanges cycle gas molar ratios of H₂/C₂ and C₆/C₂. In embodiment 62, thepolymerization process control method of embodiment 54 further includescontrolling the melt flow ratio (I₂₁/I₂) of the polyethylene from thepolymerization reactor by adjusting one or more of a H₂/C₂ gas moleratio, H₂/C₂ weight feed ratio, a C₄ to C₂ co-monomer gas mole ratio orthe C₄ to C₂ weight feed ratio. In embodiment 63, the polymerizationprocess control method of embodiment 54 further includes controlling themelt flow ratio (I₂₁/I₂) of the polyethylene from the polymerizationreactor by adjusting one or more of a H₂/C₂ gas mole ratio, H₂/C₂ weightfeed ratio, a C₆ to C₂ co-monomer gas mole ratio or the C₆ to C₂ weightfeed ratio. In embodiment 64, the polymerization process control methodof embodiment 54 further includes varying a weight concentration of thealkyl aluminum co-catalyst in the polymerization reactor whileperforming the polymerization reaction, thereby implementing apredetermined change in at least the LCB so as to bring the LCB in thepolyethylene into compliance with a predetermined product specificationset. In embodiment 65, the polymerization process control method ofclaim 64 includes: generating electron donor-free Ziegler-Natta catalystproductivity data and LCB data from polyethylene produced while varyingthe weight concentration of the alkyl aluminum co-catalyst in thepolymerization reactor; and developing the predetermined relationshipbetween the electron donor-free Ziegler-Natta catalyst productivity andthe LCB from the electron donor-free Ziegler-Natta catalyst productivitydata and LCB data. In embodiment 66, the polymerization process controlmethod of embodiment 54 further includes controlling the electrondonor-free Ziegler-Natta catalyst productivity of the polyethylene fromthe polymerization reactor by adjusting the weight concentration of thealkyl aluminum co-catalyst in the polymerization reactor. In embodiment67, the polymerization process control method of embodiment 54 furtherincludes adjusting a feed rate of the electron donor-free Ziegler-Nattacatalyst to maintain a constant polyethylene production rate from thepolymerization reactor, where deviations in catalyst productivityfunction as a leading indicator to impending changes in the polymer MFRand/or LCB or where decreasing the weight concentration of the alkylaluminum in the polymerization reactor increases the productivity of theelectron donor-free Ziegler-Natta catalyst relative to the productivitybefore the change in weight concentration. In embodiment 68, thepolymerization process control method of embodiment 54 provides that thepolyethylene has LCB greater than about 0.01 per 1,000 carbon atoms andless than about 0.07 per 1,000 carbon atoms. In embodiment 69, thepolymerization process control method of embodiment 54 provides that thepolyethylene has LCB between about 0.05 and 0.06 per 1,000 carbon atoms.In embodiment 70, the polymerization process control method ofembodiment 54 provides that the LCB is composed of 4 or more carbonatoms. In embodiment 71, the polymerization process control method ofembodiment 54 provides that the polyethylene has a ratio ofweight-average molecular weight calculated using a light scattering (LS)detector to weight-average molecular weight calculated using arefractive index (RI) detector, M_(w) (LS)/M_(w) (RI), of from about 1.4to about 3.0. In embodiment 72, the polymerization process controlmethod of embodiment 54 provides that the polyethylene has a melt flowratio (I₂₁/I₂) ranging from about 35 to about 55 or a density of from0.91 g/cm³ to about 0.965 g/cm³. In embodiment 73, the polymerizationprocess control method of embodiment 54 provides that the electrondonor-free Ziegler-Natta catalyst is formed by a process that includes:combining one or more supports with one or more magnesium-containingcompounds under reaction conditions to form a first reacted product;combining one or more chloro substituted silanes with the first reactedproduct under reaction conditions to form a second reacted product; andcombining one or more titanium halides with the second reacted productunder reaction conditions to form the electron donor-free Ziegler-Nattacatalyst, wherein the one or more supports comprises silica, alumina, ora combination thereof wherein the one or more magnesium-containingcompounds has the formula: R¹—Mg—R², wherein R¹ and R² are independentlyselected from the group consisting of hydrocarbyl groups and halogenatoms. In embodiment 74, the polymerization process control method ofembodiment 54 provides that the polymerization reactor is selected fromthe group consisting of a solution reactor, a slurry loop reactor, asupercritical loop reactor, a stirred-bed gas-phase reactor, or afluidized-bed, gas-phase reactor. In embodiment 75, the polymerizationprocess control method of embodiment 54 provides that the alkyl aluminumco-catalyst is selected from triethylaluminum (TEAl),triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum, trimethylaluminum or any combination thereof.

What is claimed is:
 1. A polymerization process control method,comprising: performing a polymerization reaction in a polymerizationreactor to produce polyethylene, wherein the polymerization reaction iscatalyzed by an electron donor-free Ziegler-Natta catalyst and an alkylaluminum co-catalyst with ethylene and optionally one or more comonomersto produce the polyethylene; removing a portion of the polyethylene fromthe polymerization reactor; measuring a melt flow ratio (I₂₁/I₂) of thepolyethylene removed from the polymerization reactor to determine theamount of long chain branching (LCB) using a predetermined relationshipbetween the melt flow ratio (I₂₁/I₂) and the LCB; and controlling anamount of long chain branching (LCB) of the polyethylene from thepolymerization reactor by adjusting a weight concentration of the alkylaluminum co-catalyst present in the polymerization reactor.
 2. Thepolymerization process control method of claim 1, wherein adjusting theweight concentration of the alkyl aluminum co-catalyst present in thepolymerization reactor is done by changing a mole ratio of the alkylaluminum co-catalyst to active metal in the electron donor-freeZiegler-Natta catalyst.
 3. The polymerization process control method ofclaim 1, further including varying a weight concentration of the alkylaluminum co-catalyst in the polymerization reactor while performing thepolymerization reaction, thereby changing the melt flow ratio (I₂₁/I₂)of the polyethylene from the polymerization reactor to make apredetermined change in at least the LCB or to bring the LCB in thepolyethylene into compliance with a predetermined product specificationset.
 4. The polymerization process control method of claim 3, including:generating melt flow ratio (I₂₁/I₂) data and LCB data from polyethyleneproduced while varying the weight concentration of the alkyl aluminumco-catalyst in the polymerization reactor; and developing thepredetermined relationship between the melt flow ratio (I₂₁/I₂) and theLCB from the melt flow ratio (I₂₁/I₂) data and LCB data.
 5. Thepolymerization process control method of claim 1, wherein controllingthe amount of LCB includes decreasing the weight concentration of thealkyl aluminum co-catalyst present in the polymerization reactor toincrease the LCB of the polyethylene produced in the polymerizationreactor.
 6. The polymerization process control method of claim 1,wherein the polyethylene has LCB greater than about 0.01 per 1,000carbon atoms and less than about 0.07 per 1,000 carbon atoms and whereinthe polyethylene has a melt flow ratio (I₂₁/I₂) ranging from about 35 toabout 55 or a density of from 0.91 g/cm³ to about 0.965 g/cm³.
 7. Thepolymerization process control method of claim 1, wherein the electrondonor-free Ziegler-Natta catalyst is formed by a process that comprises:combining one or more supports with one or more magnesium-containingcompounds under reaction conditions to form a first reacted product;combining one or more chloro substituted silanes with the first reactedproduct under reaction conditions to form a second reacted product; andcombining one or more titanium halides with the second reacted productunder reaction conditions to form the electron donor-free Ziegler-Nattacatalyst, wherein the one or more supports comprises silica, alumina, ora combination thereof wherein the one or more magnesium-containingcompounds has the formula: R¹—Mg—R², wherein R¹ and R² are independentlyselected from the group consisting of hydrocarbyl groups and halogenatoms.
 8. The polymerization process control method of claim 1, whereinthe alkyl aluminum co-catalyst is triethylaluminum (TEAl),triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum, trimethylaluminum or any combination thereof. 9.The polymerization process control method of claim 1, wherein thepolymerization reactor is selected from the group consisting of asolution reactor, a slurry loop reactor, a supercritical loop reactor, astirred-bed gas-phase reactor, or a fluidized-bed, gas-phase reactor.10. A polymerization process control method, comprising: performing apolymerization reaction in a polymerization reactor to producepolyethylene, wherein the polymerization reaction is catalyzed by anelectron donor-free Ziegler-Natta catalyst and an alkyl aluminumco-catalyst with ethylene and optionally one or more comonomers toproduce the polyethylene; measuring an electron donor-free Ziegler-Nattacatalyst productivity of the polyethylene from the polymerizationreactor; determining an amount of long chain branching (LCB) of thepolyethylene from the polymerization reactor using the measured electrondonor-free Ziegler-Natta catalyst productivity and a predeterminedrelationship between the electron donor-free Ziegler-Natta catalystproductivity and the LCB; and controlling an amount of LCB of thepolyethylene from the polymerization reactor by adjusting a weightconcentration of the alkyl aluminum co-catalyst present in thepolymerization reactor.
 11. The polymerization process control method ofclaim 10, wherein adjusting the weight concentration of the alkylaluminum co-catalyst present in the polymerization reactor is done bychanging a mole ratio of the alkyl aluminum co-catalyst to active metalin the electron donor-free Ziegler-Natta catalyst.
 12. Thepolymerization process control method of claim 10, further includingvarying a weight concentration of the alkyl aluminum co-catalyst in thepolymerization reactor while performing the polymerization reaction,thereby implementing a predetermined change in at least the LCB so as tobring the LCB in the polyethylene into compliance with a predeterminedproduct specification set.
 13. The polymerization process control methodof claim 12, including: generating electron donor-free Ziegler-Nattacatalyst productivity data and LCB data from polyethylene produced whilevarying the weight concentration of the alkyl aluminum co-catalyst inthe polymerization reactor; and developing the predeterminedrelationship between the electron donor-free Ziegler-Natta catalystproductivity and the LCB from the electron donor-free Ziegler-Nattacatalyst productivity data and LCB data.
 14. The polymerization processcontrol method of claim 10, where deviations in catalyst productivityfunction as a leading indicator of impending changes in a polymer MFRand/or LCB, the method further including responding to the deviations incatalyst productivity by adjusting the weight concentration of the alkylaluminum co-catalyst in the polymerization reactor and/or changing amole ratio of the alkyl aluminum co-catalyst to active metal in theelectron donor-free Ziegler-Natta catalyst whereby the electrondonor-free Ziegler-Natta catalyst productivity of the polyethylene fromthe polymerization reactor is controlled.
 15. The polymerization processcontrol method of claim 10, where deviations in catalyst productivityresult in changes in the production rate from the polymerization reactorand function as a leading indicator of impending changes in a polymerMFR and/or LCB, the method further including responding to thedeviations in catalyst productivity by adjusting a feed rate of theelectron donor-free Ziegler-Natta catalyst whereby a constantpolyethylene production rate from the polymerization reactor ismaintained while adjusting the weight concentration of the alkylaluminum co-catalyst in the polymerization reactor and/or changing amole ratio of the alkyl aluminum co-catalyst to active metal in theelectron donor-free Ziegler-Natta catalyst to control the polymer MFRand/or an amount of LCB.
 16. The polymerization process control methodof claim 10, further comprising decreasing the weight concentration ofthe alkyl aluminum in the polymerization reactor thereby increasingproductivity of the electron donor-free Ziegler-Natta catalyst relativeto the productivity before the change in weight concentration.
 17. Thepolymerization process control method of claim 10, wherein decreasingthe weight concentration of the alkyl aluminum co-catalyst present inthe polymerization reactor increases the LCB of the polyethyleneproduced in the polymerization reactor.
 18. The polymerization processcontrol method of claim 10, wherein the polyethylene has LCB greaterthan about 0.01 per 1,000 carbon atoms and less than about 0.07 per1,000 carbon atoms and wherein the polyethylene has a melt flow ratio(I₂₁/I₂) ranging from about 35 to about 55 or a density of from 0.91g/cm³ to about 0.965 g/cm³.
 19. The polymerization process controlmethod of claim 10, wherein the electron donor-free Ziegler-Nattacatalyst is formed by a process that comprises: combining one or moresupports with one or more magnesium-containing compounds under reactionconditions to form a first reacted product; combining one or more chlorosubstituted silanes with the first reacted product under reactionconditions to form a second reacted product; and combining one or moretitanium halides with the second reacted product under reactionconditions to form the electron donor-free Ziegler-Natta catalyst,wherein the one or more supports comprises silica, alumina, or acombination thereof wherein the one or more magnesium-containingcompounds has the formula: R¹—Mg—R², wherein R¹ and R² are independentlyselected from the group consisting of hydrocarbyl groups and halogenatoms.
 20. The polymerization process control method of claim 10,wherein the alkyl aluminum co-catalyst is triethylaluminum (TEAl) orcomprises triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum,tri-n-octylaluminum, trimethylaluminum, or any combination thereof. 21.The polymerization process control method of claim 10, wherein thepolymerization reactor is selected from the group consisting of asolution reactor, a slurry loop reactor, a supercritical loop reactor, astirred-bed gas-phase reactor, or a fluidized-bed, gas-phase reactor.22. A polymerization method, comprising: performing a polymerizationreaction in a polymerization reactor to produce polyethylene, whereinthe polymerization reaction is catalyzed by an electron donor-freeZiegler-Natta catalyst and an alkyl aluminum co-catalyst with ethyleneand optionally one or more comonomers to produce the polyethylene;removing a portion of the polyethylene from the polymerization reactor;measuring a melt flow ratio (I₂₁/I₂) of the polyethylene removed fromthe polymerization reactor; and determining an amount of long chainbranching (LCB) of the polyethylene from the polymerization reactorusing the measured melt flow ratio and a predetermined relationshipbetween the melt flow ratio (I₂₁/I₂) and the LCB.